Kim! Hi! Itโ€™s your dad!๐Ÿ‘‹ ▪ Khalilah, Iโ€™m proud of you for taking a risk for your dream.Everyoneโ€™s explanations tend to be so on-point, and the commiseration makes me feel better, too!Hi Hira. You are doing a good job!Hey Shariq! Doing a great job!                       want to add a fly-by? email us! ๐Ÿ˜Š
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NBME 19 Answers

Question#1 (reveal difficulty score)
53 yo woman w/GERD. Diet change, stress ...

Question#7 (reveal difficulty score)
48 yo woman, 2 weeks of fever and stool with ...
Entamoeba histolytica๐Ÿ”,๐Ÿ“บ

Question#24 (reveal difficulty score)
62 yo woman with sudden weakness of left leg; ...
Right anterior cerebral artery๐Ÿ”,๐Ÿ“บ

Question#34 (reveal difficulty score)
12 yo girl unable to walk for 5 days but is ...
Conversion disorder๐Ÿ”,๐Ÿ“บ

Question#35 (reveal difficulty score)
5 yo boy, R eye pain for 1 week; retinal exam ...
Retinal cells๐Ÿ”,๐Ÿ“บ

Question#36 (reveal difficulty score)
36 yo woman presents to ED after believing ...
Panic disorder๐Ÿ”,๐Ÿ“บ

Question#48 (reveal difficulty score)
62 yo man, right-handed, suffers decreased ...
Area labeled by letter 'A'๐Ÿ”,๐Ÿ“บ

Question#5 (reveal difficulty score)
38 yo woman, 6 months depressed mood, joint ...
Lyme disease๐Ÿ”,๐Ÿ“บ

Question#6 (reveal difficulty score)
24 yo man, generalized tonic-clonic seizure; ...
Psychogenic polydipsia๐Ÿ”,๐Ÿ“บ

Question#8 (reveal difficulty score)
Retinoic acid receptors and HOX gene products ...
Transcription factors๐Ÿ”,๐Ÿ“บ

Question#17 (reveal difficulty score)
Scurvy symptoms associated with decreased ...
Prolyl hydroxylase๐Ÿ”,๐Ÿ“บ

Question#23 (reveal difficulty score)
10 yo girl, slightly painful 2 mm ...

Question#34 (reveal difficulty score)
Mechanism by which action potentials permit ...
Transmission along T tubules๐Ÿ”,๐Ÿ“บ

Question#45 (reveal difficulty score)
Pathway of the transepithelial transport of water
Pathway denoted by letter 'C'๐Ÿ”,๐Ÿ“บ

Question#46 (reveal difficulty score)
Decreased pulmonary artery pressure ...

Question#5 (reveal difficulty score)
30 yo woman, 1 week of visual difficulty
Right optic nerve๐Ÿ”,๐Ÿ“บ

Question#9 (reveal difficulty score)
Cells most responsible for graft rejection?
T lymphocytes๐Ÿ”,๐Ÿ“บ

Question#19 (reveal difficulty score)
30 yo man and 24 yo woman; best estimate that ...
1 in 600๐Ÿ”,๐Ÿ“บ

Question#22 (reveal difficulty score)
Blood gas values: arterial O<sub>2</sub> ...

Question#27 (reveal difficulty score)
74 yo man; continuous systolic-diastolic ...
Renal artery stenosis๐Ÿ”,๐Ÿ“บ

Question#28 (reveal difficulty score)
40 yo man, 1 month increasing malaise, ...

Question#29 (reveal difficulty score)
15 yo girl receives bone marrow transplant; ...
Nonautologous donor๐Ÿ”,๐Ÿ“บ

Question#39 (reveal difficulty score)
45 yo man, lost outdoors in the Rocky ...

Question#40 (reveal difficulty score)
25 yo woman requests prenatal diagnosis at 12 ...
Chorionic villi sampling๐Ÿ”,๐Ÿ“บ

Question#42 (reveal difficulty score)
Study conducted to determine effects of drug ...

Question#46 (reveal difficulty score)
52 yo man, sudden onset of substernal chest pain

Question#50 (reveal difficulty score)
39 yo man, 6 months of headache, muscle ...
Basophilic stippling๐Ÿ”,๐Ÿ“บ

Question#13 (reveal difficulty score)
26 yo woman after jejunoileal bypass for ...
Vitamin A๐Ÿ”,๐Ÿ“บ

Question#14 (reveal difficulty score)
11 yo boy, right mid-thigh pain for 2 weeks; ...
Ewing sarcoma๐Ÿ”,๐Ÿ“บ

Question#15 (reveal difficulty score)
60 yo woman, 1 year of episodic involuntary ...

Question#27 (reveal difficulty score)
52 yo woman prescribed cisplatin for ...

Question#46 (reveal difficulty score)
24 yo woman; renal oxygen consumption found ...
Tubular reabsorption๐Ÿ”,๐Ÿ“บ

Question#0 (reveal difficulty score)
During an experiment, an isolated skeletal ...

Question#0 (reveal difficulty score)
A newborn delivered at term to a ...

clotting moa

Question#0 (reveal difficulty score)
Investigator studying spermatogenesis...tight ...

Question#0 (reveal difficulty score)
23-year-old woman...heparin...decreased ...
Antiplatelet antibodies๐Ÿ”,๐Ÿ“บ

Question#0 (reveal difficulty score)
Graph shows rate of breakdown of skeletal ...
Allosteric activator๐Ÿ”,๐Ÿ“บ

Question#0 (reveal difficulty score)
During an experiment, a researcher blocks the ...
Retrograde axonal transport๐Ÿ”,๐Ÿ“บ

Question#0 (reveal difficulty score)
Investigator does an experiment... third ...

Question#0 (reveal difficulty score)
A 2-year-old boy with cerebral palsy is ...

Question#0 (reveal difficulty score)
An 11-year-old boy has repeated episodes of ...
NADPH oxidase๐Ÿ”,๐Ÿ“บ

Question#0 (reveal difficulty score)
A 35-year-old man comes to the physician to ...

Question#0 (reveal difficulty score)
A 30-year-old man develops urinary ...
pelvic nerves๐Ÿ”,๐Ÿ“บ

Question#40 (reveal difficulty score)
Immediately after cerebral infarction, a ...
A (Broca's area)๐Ÿ”,๐Ÿ“บ

FA19p490 stroke neuro

Question#23 (reveal difficulty score)
A 22-year-old man get separate from a group ...
Area postrema๐Ÿ”,๐Ÿ“บ

Question#24 (reveal difficulty score)
A 62-year-old woman has an abdominal aortic ...
Cholesterol emboli๐Ÿ”,๐Ÿ“บ

Question#11 (reveal difficulty score)
A 48-year-old man comes to the physician for ...
Budd-Chiari syndrome๐Ÿ”,๐Ÿ“บ

Question#35 (reveal difficulty score)
52 yo woman, right-dominant coronary ...
left ventricle๐Ÿ”,๐Ÿ“บ

Question#17 (reveal difficulty score)
During a study of the digestion of protein ...

Question#42 (reveal difficulty score)
A 61-year-old man has erectile dysfunction ...
D (corpus cavernousum)๐Ÿ”,๐Ÿ“บ

Question#8 (reveal difficulty score)
An investigator is developing a new drug that ...
Crypt cells๐Ÿ”,๐Ÿ“บ

Question#27 (reveal difficulty score)
A 6-year-old girl has the recent onset of ...
Procollagen, type I๐Ÿ”,๐Ÿ“บ

Question#6 (reveal difficulty score)
A 24-year-old woman comes to the gynecologist ...

Question#26 (reveal difficulty score)
A 2-year-old boy is brought to the physician ...
Bruton agammaglobinemia๐Ÿ”,๐Ÿ“บ

Question#39 (reveal difficulty score)
A 52-year-old woman begins treatment with ...

Question#4 (reveal difficulty score)
A 50-year-old man comes to the physician ...

Question#49 (reveal difficulty score)
A 30 year old man is brought to the ED 30 min ...
sympathomimetic agent๐Ÿ”,๐Ÿ“บ

Recent comments ...

... aliyah made a comment on nbme19/block1/q#35 (5 yo boy, right eye pain 1 week)
submitted by aliyah(35)
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If a rmeg clle or sacmtoi llce adh teh oingirla ti,nmutao hnte tee'srh na esrancide skri for rencac ni eroth tarps of eht dboy .oftI o onyl letniar cesll in one eey is dt,autem only tath eno eye si at iksr fro rac.ecn

... ajguard26 made a comment on nbme19/block2/q#16 (40 yo woman, chorionic villus sampling)
submitted by ajguard26(41)
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Coihicrno ilvli amilpngs is the iknatg fo cgeeitn rmaaleti hiintw ni eht riohnoicc lvili of eht nlctpae.a iConrhico lgpsmain is dnoe hnew a tpeaitn is ta ihgh sikr rof chmorsmloao brenmalosatii oru(vesip tt,ess y53o ro rloe,d yfialm .)xh dinurg eth 301-1 keews fo c.ngynaerp

doenfnCi alalcpnet msioascim lretuss hwen the .VSC.. etnsgit semco acbk kcab gnhwois a rtms,iyo ubt all quusesentb gnsitet and( eth stufe es)fitl veah lroanm lramhocmoso tnosc.u sThi yam eb ued ot eehirt a balsitrtohcpo oatiunmt, or by mriti"ocs rs,ecue" in wchih itscomri llsce htta erew pdeospsu ot eb ni eht uesft era ndficnoe ot hte lncaetpa to pvtneer na aamonrlb .futes

cbay0509  thank you +
shakakaka  Why It's unreadable.. +3
randi  unfortunately you have to have an account to unscramble most responses +
chaosawaits  Wow, a +16 response (rarely see those) that we can't read... FML +
... cassdawg made a comment on nbme19/block3/q#50 (39 yo man, 6 months of headache, muscle aches, fatigue; distal motor weakness of extremities)
submitted by cassdawg(1398)

So I hate this question because you can know what the diagnosis is and still miss it.

TL;DR: This is lead poisioning, so there is basophilic stippling in a peripheral blood smear [BUT ringed sideroblasts would also be found in the bone marrow]

Why this is lead poisoning: (FA2020 p425)

  • Microcytic Anemia (caused by lead inhibition of ferrocheletase and ALA dehydratase)
  • Environmental exposure (ammunition at the range, he is an officer)
  • GI effects (crampy abdominal pain)
  • Neurological effects (headache, irritability, distractability, forgetful, motor weakness)

Why it is NOT the other answers:

  • Auer rods - characteristic of acute myelogenous leukemia which would present with pancytopenias (his WBCs are normal) along with circulating myeloblasts on peripheral smear; median age onset 65 years and he has no risk factors
  • Oval Macrocytes - in macrocytic anemias (B12 or folate deficiency), this is microcytic as indicated by MCV
  • Pleomorphic lymphocytes - occur in chronic lymphocytic leukemias and infectious mono, both which have different symptomotologies
  • Ringed sideroblasts - are from lead poisoning but are in the bone marrow
  • Scistocytes - characteristic RBC which has been through a clogged vessel and sheared off, found in microangiopathic hemolytic anemias (MAHAs) like thrombotic microangiopathies like TTP and HUS (typically normocytic anemia and different presentation; a question would likely give you more info on the thrombolytic pathway if they wanted you to choose this; we didn't even get a platelet count here)
  • Target Cells: found in HbC disease (glutamic acid to lysine in hemoglobin, causes extravascular hemolysis), liver disease, asplenia, and Thalassemia (deletions in either alpha or beta chain of hemaglobin, causes anemia that would be present from childhood and would not have neuro symptoms)
ftr_dr_bowowers  thank you! +3
chaosawaits  just take my upvote you beautiful sonofabitch! +
chaosawaits  So if FRC decreases, TLC decreases as well, which rules out E. +
chaosawaits  Above comment not related to this question +
... ajguard26 made a comment on nbme19/block1/q#1 (53 yo woman with GERD.)
submitted by ajguard26(41)
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oS lhagtuho ptsoisMrloo SDEO aseeicnr cusum orotipdncu nda si i-votgpseeactrtor (and in AF dseo tseat ttha ti eecasedrs icda ti)ncurdo,po ehrbyte ieenacsgdr mosyptms adn adingi in eahig,nl ermleazpoo is eth re"mo erroc"ct eohicc. This si cuseaeb peloeoarzm si a p-mopuntrpo btri,inhio ihwhc illw act irteldcy no eth nrtopo pspmu fo het atoschm and ceadsree the figndonfe tegna oemr tahn the opilosmosrt li.wl r,oefTeehr ti si het rfsit elin rudg rof ED.RG

an_improved_me  These questions can be so frustrating... I mean most people know PPIs are your go to when considering GERD / peptic ulcer disease... but when you speicfically add "both relieving Sx ... promoting healing", why even add a drug that specifically and directly does both... I mean PPIs promote healing, but so indirectly. This hurts my heart +3
chaosawaits  Seriously, FA2019, p393 specifically states misoprostol "increases production and secretion of gastric mucous barrier and decreases acid production" What does it say for omeprazole, you might ask? "Irreversibly inhibits H+/K+ ATPase in stomach parietal cells" and that's it. +
... peteandplop made a comment on nbme19/block0/q#0 (76-year-old-man...severe substernal chest...)
submitted by peteandplop(38)

This patient is presenting with with STEMI (FA2019 p301), thus the entire vessel must be occluded. Coronary vasospasm via a1 stimulation (increased smooth muscle contraction) would lead to these findings.

As far as the nitro aspect, I think this could be referring to pt history of ischemic heart disease, and the scenario of coronary steal, however I don't think you would need that to answer this question (and I could be going down an unnecessary rabbit hole of misery).

Other helpful pages are FA2019 p238, a1 sympathetic stimulation results in increased vascular smooth muscle contraction.

Last, big ups to the brother for setting arguments aside and still taking his hermano to the emergency department. Perhaps they were arguing at who responded to COVID-19 and medical education worse: USMLE or Prometric.

prolific_pygophilic  ^Comment of they year +1
chaosawaits  Who else got a little distracted by the tragic story of watching your brother have a heart attack because of an argument you were having with him and then had to refocus to get this question? +
an1  wouldn't coronary vasospasm refer to prinzmetal angina? can someone go over the other options? +
... aliyah made a comment on nbme19/block1/q#17 (29 yo man untreated HIV)
submitted by aliyah(35)
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Aterf hte D+4C ellsc eebmco enfc,tedi eht 8C+D llecs ilkl m.the

cbreland  Same for the macrophages and dendritic cells that would be infected. Intracellular pathogen that would need to have CD8 T cell mediated death +2
vetafig692  After the CD4+ cells become infected, the CD8+ cells kill them. +1
... drdoom made a comment on nbme19/block1/q#4 (66 yo man, 2 months no erection)
submitted by drdoom(969)
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yitiInbla ot aiainmtn na ctneiroe = eliecrte sdynftiounc. oS wno eht qeituson si h?W"y"

gteaFui, udfiilfytc spnegeil, ituifcldyf togrinccnaent is rttgansi to undso eilk rdiesensop. iyctif"Dlfu gcnerciatto"nn tmihg be etenrpdteri sa idraeimp eieuetxvc otnucinf or teh ennbginigs of earcde-tvaralslu eniedtam mante(ide eertlad to mlals tub urnumeos erlacrbe aistnf,c)r btu on tpSe 1 nmedeita llwi eb tbtaaln .(i,e. ol"ts ish wya hoem," giren""n,wad t.e).c

sDepeoinrs is ytlualac mmocno efrta a aeititdblnig enevt elki koers,t as ouy timgh pt.cxee hiWt epniossedr cosem a lsos of usxeal sniteetr nad terdโ€”eshtia si dcareseed dbolii.

enO can emka the gaertnmu tath a lcsravau" in"ttpae htimg ahve seom isuses whti his "ep"pis rrastiorisels,e(oc stpatcearahitpmihcpmaesyt/y tnyuodi)cfns d,an ofr stih es,rnoa clrtnauon ereoinct hsudlo be aecddeers; but teno thta hotgnni si ietnmdeno touab dsilnt-angong salrcuav ediases on( hx fo hnsotr.ene)pyi

sA a ust,lre hte etsb nseawr cihoce ehre is C. iob(diL ecdrseade tbu oraltcnun tneioecrs maor)n.l hTe ibg tosuqien I vahe is, hwo eth echk soed shti gyu wonk h'es arhd nhwe seh' els?a!ep! :p

cbay0509  thank you +1
ilikedmyfirstusername  there are several UWorld questions about psychogenic ED with the answer being normal libido and normal nocturnal erections, idgi +14
djeffs1  Yeah NBME says its C, but I still think with a recent stroke you can't bank on normal nocturnal erections... +
drdoom  @djeffs nocturnal erections happen at the level of the spinal cord (S2โ€“S4)! a โ€œbrain strokeโ€ (UMN damage or โ€œcortical damageโ€) would not kill your ability to have nocturnal erections! +
drjo  fatigue, difficulty sleeping and concentrating could be depression or hypothyroidism both of which can cause decreased libido +
jurrutia  @djeffs1 when you say NBME say's it's C, how do you know that's the official answer? Did NBME post the answers somewhere? +
djeffs1  in the versions I purchased from them they highlight the correct answer in the test review +1
shieldmaiden  For me the keyword in the stem is "maintain"; he can maintain an erection, therefore nocturnal erections must be normal. Libido, on the other hand, is psychologically driven, so if he is depressed (trouble sleeping, concentrating, fatigue, recent major health problem) then the strength towards any kind of desire, including sexual, will be low +1
chaosawaits  His nocturnal erections are normal because his spinal cord is not damaged. His libido has decreased because he's showing signs of depression. +
... shadowbox made a comment on nbme19/block3/q#19 (30 yo man and 24 yo woman; best estimate that child will have oculocutaneous albinism?)
submitted by shadowbox(15)
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ecinS eht stfrae'h ibnislg is cdtefafe, ew know tath hte 'srftaeh taresnp are tobh e.sriracr Ttah nemsa het leopssib ngteyeops of eht taferh era AA, A,a Aa, or .aa

We wokn het hafter si adnf,teucfe os htta msena eh conant be a,a dna stmu be hritee ,AA ,Aa or .aA

encSi heetr rae nylo 3 rdftifene egysnetpo eh udlco eh,av htwi 2 of mthe eigbn rerirca ogeypsne,t rteeh is a 2/3 ypibtirolab he is a

So we ntaoib the yaoitibplrb of teh rhatfe apssgni no a ivceessre laeell sa /32 ibb(rytpaoil of ebnig a crie)rar x /21 ipi(btolyabr of aginpss on a eervsscie lealel if eh is a rarr.)cei Teh 32/ is otn treaveln to the latrbipioyb atth hte othemr is a ra.iercr

We nwko eth fyunqeecr fo deectffa uviaisdindl in teh pnpioautol ta alrge si /000,104 ()q=2,^ so =1q002./

,1=q+P os 29=p9/010 and 10202.099(21(/=0)qp/)2

oT kema ntpcmlltiuoiia aierse ew umessa 2199=10/0, :so

=q21=01/22/0)00*p(1 ;--> hsit si hte craerir feqecyrun .a(.ak., zo)tsghreeetoy ni hte l,unooippat ihchw we nac ussmae for teh .morhte

oS, ot rewnsa the tenrie uensqtio ew mtlilpyu hte pytobilbrai ttha hefrta si a arreric )2(/3 dan saesps no eht elalle /)1(2 tmeis het tiarplbyoib that othrem si a arrrice 10)(/01 dna epssas on the alelel 2)1/;( tigtnpu it lla thegoret ew h:eav

3))10(02((*2/1)*)*1(//1/2 = 00/212 = 0610/

cbay0509  thank you +
garble  Why is it assumed that the mother is a carrier? Couldn't it also be possible the mother is unaffected and not a carrier? +1
garble  Turns out the difference is negligible, nevermind. +
chaosawaits  Who added all these questions with abbreviated stems? fml +
chaosawaits  The chance of the mother being a carrier is 2/3 because she's obviously not homozygous (so there are only three possibilities for her, 2 of which she is a carrier). Take the square root of 40,000 to get q = 200. (2/3) * (1/2) * 200 = 600 +1
... cassdawg made a comment on nbme19/block3/q#22 (Blood gas values: arterial O<sub>2</sub> pressure: 96 mm Hg; Arterial O<sub>2</sub> content: 12.0 vol%)
submitted by cassdawg(1398)

This is my best interpretation with a source and paragraph from the source listed:

In anemia, hemoglobin available is decreased. This causes decreased oxygen binding, and ultimately less oxygen is available for release onto tissues.

  • PaO2 will be normal-ish because the arterial blood will still equilibrate in the lungs even though the hemoglobin binding is decreased (think of CO poisoning where PaO2 looks normal).
  • Arterial O2 content is actually decreased because there is less oxygen total available (less hemoglobin bound to oxygen)
  • Mixed venous O2 content (%) is decreased for a similar reason and also for the reason listed below
  • Venous PO2 is slightly decreased because there is higher oxygen extraction at tissues due to the compensatory mechanisms from less total O2 being delivered and less O2 being unloaded (since there is less hemaglobin bound O2 in the first place in anemia)
  • PCO2 is normal-ish for similar reasons to the first bullet

"The circulatory adjustments in response to anemia will be similar to those of the preceding case. In order to maintain tissue oxygen consumption at baseline levels associated with a normal oxygen carrying capacity of blood, the reduction in oxygen delivery will lead to an increase in capillary perfusion, and oxygen extraction will increase. Arteriolar dilation and viscosity reduction (for the case of a reduction in Hct) will cause blood flow and oxygen delivery to increase. Both oxygen extraction and oxygen delivery will continue to increase until the oxygen requirements of the tissues are met or until the capacity to increase oxygen extraction and delivery has been reached. The resulting situation is one in which venous oxygen content and PvO2 are less than normal. Since PaO2 is normal for all the anemic situations considered, this defect is not sensed by the respiratory chemoreceptors. Thus, increasing the inspired oxygen fraction is not helpful except for the case of CO poisoning, where high inspired oxygen (e.g., 100% oxygen at ambient barometric pressure or placement of the subject into a hyperbaric chamber) competes with CO binding at the heme site (recall Haldane's first law)." -

blueberriesyum  Also, in first aid respiratory chapter for anemia it says, Hb conc is low, %O2 sat is normal, dissolved oxygen (PaO2) is normal, but total O2 content is low. Total oxygen content is the sum of oxygen bound to Hb and dissolved oxygen. (FA 2018 pg 649) +
... corndog made a comment on nbme19/block1/q#26 (Niemann-Pick)
submitted by corndog(14)

ME: I think I finally have these stupid storage disorders down

NBME: Not so fast, partner

i_hate_it_here  Same bro +
... blueberriesyum made a comment on nbme19/block0/q#0 (A 70-year-old man develops a progressive disinhibiton)
submitted by blueberriesyum(12)

A 70 year old develops a progressive disinhibition syndrome with episodes of emotional outbursts, inappropriate use of language, and socially inappropriate behavior. Where is the most likely damage?

Answer: Frontal lobe disinhibition.

Bilateral amygdala (medial temporal lobe) would've been affected if it was Kluver Bucy Syndrome.

flapjacks  If you know the story of Phineas Gage, it can help +6
helppls  How do you tell the difference from a frontal lobe issue and Kluver Bucy Syndrome? +
nikitasr27  I would say the emotional and language part. The frontal lobe is very involved in emotions and the limbic system as well as in complex language concepts. Kluver Bucy would lack these aspects as the individual is โ€œindifferentโ€ to everything (no fear, no emotions) just like my ex +1
randi  Kluver-bucy is also marked by specific behaviors like hyperphagia, hyperorality, hypersexuality. Apparently can also be associated with HSV-1 encephalitis FA2019 p499. +1
chaosawaits  What am I looking at? From what viewpoint am I looking? Can anyone identify the labels? I have A is olfactory tract, C/D are optic nerves, E/F are optic tracts, G/H are substantia nigra of midbrain & still I am totally lost. +1
chaosawaits  I imagine that we are viewing the front of the brain from underneath and slightly angled to expose the midbrain more easily. Obviously B is the frontal lobe. But what are I and J? +
an1  @chaosawaits I think J might be the partial lobe. the only thing confusing me is that B is the frontal lobe with the amygdala is actually in the temporal lobe... +
an1  I take that back, I thought it was Kluver body for a second but its just frontal lobe stuff lol +
pakimd  can anyone explain why this is kluver bucy and not frontotemporal dementia? +
... cassdawg made a comment on nbme19/block3/q#46 (52 yo man, sudden onset of substernal chest pain)
submitted by cassdawg(1398)

Many opioids (like morphine) are potent histamine releasers, which can cause puritis and anaphylactoid reactions (such as seen in this patient with the facial flushing, drop in blood pressure and corresponding increase in heart rate). Puritis is actually a common side effect of morphine.

Source: First Aid and

solidshake  Opioids (morphine), radio contrasts, some antibiotics (vancomycin), and several other medications can trigger IgE independent mast cell degranulation. (Uworld Qid# 11852) +
... cassdawg made a comment on nbme19/block1/q#26 (Niemann-Pick)
submitted by cassdawg(1398)

Niemann-Pick is a lysosomal storage disease that is a deficiency in sphingomyelinase that leads to a buildup of sphingomyelin (Niemann picks his nose with his sphinger)

Sphingomyelinase is considered a lysosomal hydrolase

chaosawaits  I'm guessing the reason "decreased synthesis of ceramide" isn't the answer then is based on FA2019 p88. Since there are 3 different paths to make ceramide, losing one throught Niemann-Pick disease will not significantly decrease the ceramide production +
... cassdawg made a comment on nbme19/block2/q#25 (48 yo woman, 3 months fatigue; X-rays reveal generalized osteopenia)
submitted by cassdawg(1398)

Answering this question requires you understand the mechanism of osteoclast stimulation by parathyroid hormone (FA 2020 p332).

Parathyroid hormone stimulates osteoclases indirectly by stimulating the release of RANKL bu osteoblasts which will bind to RANK receptor on osteoclasts and stimulate the resorption of bone. This is a paracrine process because paracrine signaling refers to stimulation by neighboring cells (short distances).

... cassdawg made a comment on nbme19/block3/q#17 (45 yo patient, chronic alcohol dependence, foul-smelling brownish sputum)
submitted by cassdawg(1398)

I love this question because we are all obviously trained radiologists...

In reality, rather than identifying every X-ray given and trying to match it to the question stem, the best way to approach this question is to identify what his most likely issue(s) and match to the general characteristic of an X-ray, going to the X-rays looking for these characteristics.

He is an alcoholic with foul smelling (ding anaerobic) sputum. Because he is an alcoholic he is at risk for aspiration pneumonia and anaerobic pulmonary abscesses from aspiration (which is why they mentioned the bouts of blacking out). So what are the characteristics of these diseases? Aspiration pneumonia is a lobar pneumonia which would present with lobar infiltration (see here for example). Pulmonary abscess would present with cavitation and an air-fluid line (see here for example with air fluid level pointed out and here for cavitation/abscess pointed again).

Thinking of this now approach the X-rays looking for specific findings. One has the air fluid level and cavitation, so that is the answer (it is an abscess). None of the others have lobar infiltrate and are either more diffuse or hilar so they should be ruled out.

an_improved_me  The even more frustrating part of this question is that they don't show an abscess in a more dependent region of the lung! +2
... cassdawg made a comment on nbme19/block3/q#41 (41 yo woman, 34 weeks gestation; amniocentesis shows lecithin-to-sphingomyelin ratio of 1.5:1)
submitted by cassdawg(1398)

This ratio is used to determine appropriate production of lung surfactant, so this baby would not have appropriate production of surfactant if birthed at the time of the ratio calculation. It would go into neonatal respiratory distress syndrome.

TL;DR: surfactant decreases lung recoil, so the lack of surfactant in this baby will cause an increased recoil which will decrease the functional residual capacity (FA 2020 p661-662)

Surfactant is necessary to decrease surface tension of alveoli and increase compliance of the lungs (remember when the lungs have greater compliance, this makes the lungs easier to fill). Surfactant also helps to prevent alveolar collapse as the lack of surfactant allows there to be varying surface tensions between large and small alveoli (Law of Laplace), so lack of surfactant would lead to widespread atelectasis (alveolar collapse). Because surfactant serves to decrease these forces which normally favor collapse of the lung, it also serves to decrease the lung recoil.

Lack of surfactant in a baby = increased alveolar surface tension, lower compliance, more alveolar collapse, more recoil (less residual volumes)

Total lung capacity is unchanged because with enough force you can still expand the lungs to full capacity.

geekymle  hey ya! thanks for the explanation, but i'm still not able to understand why decreased functional residual capacity. +2
cassdawg  Not sure if this will help but another way of thinking of this is that it is similar to pulmonary fibrosis with decreased compliance leading to lower functional residual capacity! The only difference is here you retain total lung capacity because it is a "reversible" compliance issue (give them surfactant) and the lungs themselves are not the issue. Also, like you said in your comment, lungs won't open up so there is a lower starting point for breathing, and thus a lower functional residual capacity (volume left in the lungs after normal expiration). +4
chaosawaits  So if FRC decreases, TLC decreases as well, which rules out E +1
... cassdawg made a comment on nbme19/block4/q#14 (11 yo boy, right mid-thigh pain for 2 weeks; femur X-ray reveals single osteolytic lesion in mid-diaphysis)
submitted by cassdawg(1398)

TL;DR: This is Ewing sarcoma because it is a young boy with small blue cell bone tumor in the diaphysis of the femur

Ewing sarcoma is a malignant bone tumor common in young boys <15y.o. typically found in the diaphesis (middle) of long bones (particularly femur) or pelvic flat bones. It is a small blue cell tumor, meaning the descriptor of small, uniform, hyperchromatic cells with high nucleus:cytoplasm ratio. It also has an "onion skin" periosteal reaction in the bone (described as tissue surrounded by concentric layers of reactive bone in the question). Not mentioned is the association with t(11;22). [FA 2020 p 464]

Why the others are wrong:

  • Chondrosarcoma is a tumor of malignant chondrocytes (catilage) and found mainly in the pelvis, proximal fever, and humerus
  • Eosinophilic granuloma is is a rare, benign tumor-like disorder characterized by clonal proliferation of Langerhans cells and the most common varient of Langerhans cell histiocytosis.Would likely say something about Birbeck granules in the stem and would have associated symptoms such as rash [FA 2020 p434]
  • Multiple myeloma is a plasma cell dyscrasia [FA 2020 p431] with overproduction of (typically) IgG. Characteristics include CRAB - hyperCalcemia, Renal involvement, Anemia, Back/Bone pain due to punched out lytic bone lesions (typically of the spine)
  • Nephroblastoma/Wilm's Tumor is the most common renal malignancy of early childhood and presents as a flank mass [FA 2020 p 606]
  • Osteosarcoma (or osteogenic sarcoma) is a primary bone tumor common in men <20. It is typically found in the metaphysis (tips) of long bones. Histology shows pleiomorphic osteoid producing cells. On X-ray you would potentially see a Codman triangle (elevation of periosteum) or sunburst pattern
  • Small lymphocytic lymphoma is essentially the same thing as chronic lymphocytic leukemia. It is considered a non-Hodgkin lymphoma of B-cells and the most common leukemia of adults (as CLL). Smudge cells would likely be seen on peripheral blood smear. It would not likely present as an osteolytic lesion and is unlikely in children. [FA2020 p432]
cbay0509  thank you +
... cassdawg made a comment on nbme19/block4/q#33 (Oral fluid therapy for diarrhea caused by <i>Vibrio cholerae</i>)
submitted by cassdawg(1398)

Oral rehydration therapy commonly consists of sugar/electrolyte water because of the ability to utilize the sodium glucose symporter. Where sodium goes, water follows, so by hydrating with this mixture it allows for an osmotic "pull" of water into the intestines.

Here is an article with more detail and a pretty diagram:

ftr_dr_bowowers  thank you!!! and thanks for not having the answer scrambled smh +3
i_hate_it_here  It's not even the contributor that scrambles it, it's the nbme answers owner whose trying to make a profit of the free contributions of med students! +2
... picodemolar made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
submitted by picodemolar(5)
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necognesO htiw ngai fo ncitfonu nmaiotut dela ot radceenis ,tsptoirarnnci c.e,t eearshw uormt psrsopreus nesge bkcol -&1Sg;G-t 1FN gnee courdpt hsa RSA TGesPa ivtytcia ihhwc wkros yb naohiysoltgrphp dna gaciantitv porniet (iomurnbo.finr)e So rthee si at estal 1 roumt sesrpurpos eeng hatt krwso hgorhtu ohposayihnolrt.p

rwd1027  ่ฐ็Ÿฅ้“ไธŠ้ขๆ˜ฏไป€ไนˆ่ฏญ่จ€ๅ†™็š„ๅ†…ๅฎน๏ผŸ +
csalib2  ๅคไปฃ็ง˜ๅฏ†่ฏญ่จ€ +
pakimd  can you explain how neurofibromin works by phosphorylation? doesnt it cause hydrolysis of Ras bound GTP (by activating Ras GTPase) leading to formation of inactive Ras-GDP complex thereby downregulating Ras activity? thank you +
... metformality made a comment on nbme19/block3/q#12 (23 yo woman engages in 30 minutes of strenuous exercise)
submitted by metformality(14)
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High craaicd puutot to teh porluynma otraclnciiu udnrig xrecisee lwli aeucs the sonndteiis nad nticrrtmuee fo lmveiecssso dna ahtt wlodu eascu eth icearsne ni tlato nso-stceasrciol a.ear

rHee aer tow gsiame ttah urislattle this inielprpc yilecn:

... cassdawg made a comment on nbme19/block3/q#28 (40 yo man, 1 month increasing malaise, nausea, abdominal pain; CD8+ T lymphocytes resulting in liver injury)
submitted by cassdawg(1398)

This individual has active Hepatitis B, as evidenced by their Hepatitis B surface antigen positivity. Hepatitis B virus productively infects hepatocytes. The CD8 cells will thus attack the hepatocytes.

Another way of approaching this question is to notice AST and ALT elevation are typically indicative of hepatocyte damage.

Ito cells are the same thing as stellate cells, and their primary function is to store vitamin D and fat and produce ECM when activated. Kupffer cells are the liver's macrophages. Bile duct epithelium is not infected in hepatitis.

moms  Exactly. But Ito cells (located in space of Disse) store Vitamin A when they are quiescent and produce ECM when they are activated. Basically are responsible for hepatic fibrosis. p. 367 FA 2020. +5
... shadowbox made a comment on nbme19/block3/q#40 (25 yo woman requests prenatal diagnosis at 12 weeks gestation)
submitted by shadowbox(15)
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heT stme ttsaes tath eht hemtor si 21 ekswe etst.aonig SVC is reofpderm st1 eitmsre,tr saulluy bt/ 40-11 ewkse gnetoasit diacnrogc to t.ateDpUo-- imAno si mpfrdroee afret 51 sk.ewe Fmor Dte-Uoa-:pt nceesmiAsnotโ€œi uodlhs be morperdfe teafr 51 sweke fo ateoisgtn eecubsa iearerl docreuspre rea esls lyekli to eb uslufccss,e aer saaostcedi hiwt iehrgh tasre of clel elrtuuc fel,iaur nad ryrca geetarr faelt iskโ€s.r

... metformality made a comment on nbme19/block0/q#0 (Isolated skeletal muscle contracted with electrical stimulation)
submitted by metformality(14)
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eWhn a slmcue unsr tou fo luef e,g( guole)cs /arnod oidpucnrg ssel APT nda iโ€œsโ€ecnared ucauntmoiacl of tibsteomlae (all oreth tsonoip isebsed hte cerrotc ie,)ohcc it is a gins fo eostn fo escmul tgfiaeu. heT smte si aisgkn whihc of hte gonlolwfi iwll de,cesaโ€?eโ€œr adn it is eth pH ttha wlil ecdrease dissci(o)a deu to eht acailnmutcuo fo ctlcai adci (meremreb llscioysgy yahawpt ehwer yrvatupe steg neveorcdt to clcati cid.)a

... ajguard26 made a comment on nbme19/block1/q#24 (62 yo woman sudden weakness of left leg)
submitted by ajguard26(41)
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iThs pinatte ensstepr twih lasicsc upper rotom onnuer elison y:sptomsm essew,akn lfapiryr,xeeeh dna edeseadrc tnnos.iesa ereHwo,v teh sniqueto tetsas she "canont lelt etewrhh ehr ftel rgaet ote si sidrae ro "dseerdpse ehwn rhe seey are ,dslceo hiwch aym emka uoy srdinoceer dan tiknh theer yam eb eosm ppriciteeoprvo isuess yeht era trinyg ot itnh a.t siTh si otn hte ea.cs sypilacEel neoc yeht neiotnm hetre rae no theor abiioltmrasen .ei(,. on puerp ibml atrimlboansei or tghri sdedi sia.)lmnaoeibtr fI htsi is eht s,eac treeh si on gaeadm ot eht rttacs ta all hciwh( aer ltisl sddrenoice UM)N.

ohe,eTfrre eth madaeg is lruype rtmoo and onsyser in the tfle gle, hwhic is on teh melida catpse fo the nflator adn palateir lseob ecespltyirv.e ihTs eaar si pilesupd yb eht nairetor lreraebc a.ryetr

issamd1221  contralateral deficits +1
cbay0509  thank you +1
flapjacks  I think her 60 pack-year history suggests possible PAD and therefore loss of proprioception in the lower extremities, leading to an unfortunate distractor +1
an_improved_me  I don't understand why you would consider the propioceptive deficit a distractor... doesn't the DCML (which carries propioceptive information) project to the primary somatosensory cortex (via the VPL?). In this case, a lesion to the right anterior cerebral artery, which supplies both motor and sensory information to the lower limb would lead to somatosensory, propioceptive, and motor deficits. +1
... doofusmd made a comment on nbme19/block1/q#35 (5 yo boy, right eye pain 1 week)
submitted by doofusmd(5)
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hTsi is hwat si ownkn sa a csomiat iutmaotn: a tntmoaui taht rouscc in mngo-nnleeri lcsel dan, ,otfeerreh lnyo teffsec tguhaedr elcls derediv fmro teh enrpat cell tihw eht .tmtonaiu S,o a toatimun corerduc in a tidnteederiffa paenrt clel that agev eris to a est fo agrhutde slcle ci,hhw( ni this ase,c were seetdndi to mceoeb rtnalei eui.tss)

... ajguard26 made a comment on nbme19/block1/q#42 (Advantage of randomized controlled studies)
submitted by ajguard26(41)
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gCo"ounifndn "ivalbsare reeh msnea "nidougconfn bi,as" sllsaieyte.n ndA this is uret ebecusa a ciereppstvo roocht ooskl at a fisccpie eexusrpo ot a btnscuesa veaotrm(lnienn ot,ixn u,gdr tc).e, dna akss "oWh liwl levdope itsh adesies fi ?pee"xods 'sCPS loko tmettpa to ifdn a etvaelir srki saaetcsdoi iwth na up.xeoser hTey do ton ktea onti ucctona eth tcfeafs hotre rxesusep.o hsTi si ruoy oncnnfduigo .sbia FA segvi hte ealmepx fo cgdnuofonin isab sa mlyr"uonaP eieadss is ermo ocomnm in sewokrr in a loac ;emni rw,oheve mensir are reom lyleik to se,ko"m dan nsice nsmiogk cna olsa lead to rmyunlpao asdeies, yuo tacn' erllya sya hrtwhee the sgimnko sfri(t or sodnec d)nha or het ocal udst ssaeuc eth emblop.r A cicillna ,atilr on eht throe h,nad ninotcsa a stet opurg nad a rtcooln prguo, os eavasbilr hcsu as the uoonficngdn iaaerbvl eonidtmen oebav rae iei.tmld

winnshak  unscramble plz +
... cassdawg made a comment on nbme19/block1/q#44 (Best testing strategy when treatment has serious side effects)
submitted by cassdawg(1398)

TL;DR: You want the most sensitive test first to rule out the disease in negatives (least likelihood of false negative) and the most specific test next to "rule in" only true positives (least likelihood of false positives) [FA2020 p257]

The way I always think of sensitivity and specificity is in relation to false negatives and false positives.

  • High Se N setivity means you are less likely to have false Negatives (someone who has the disease but tests negative)
  • High s P eceificity means you are less likely to have false Positives (someone who tests positive but does not have the disease)

In this question, you want to ensure you are only treating those who actually have the disease, or in other words that you want to minimize your false positives. The best way to do this is maximize sPecificity. Test 1 has 100% specificity meaning it will have essentially NO false positives which is great so we definitely want to use it (eliminating all but two options)! The better way to ensure you are catching as many cases as possible while still only getting true positives is to test with test 3 first, which has a much higher sensitivity. That way we are ruling out disease in the negatives of test 3. This also adds to our ability to only truly treat those with disease as we have ruled out disease in our first negative population, then we test the positives to "rule in" disease with a highly specific test.

The issue with using Test 1 first and only testing the positives is we know the positives from test 1 are likely true positives, as the highly specific test would have a basically zero false positive rate. At that point there would be no point in testing with test 3, as we have basically a true positive population. The issue is we have missed a lot of diseased due to the low sensitivity and high false negative rate of test 1.

Another way to think of this is to remember the formulas (as seNsitivity contains false Negatives, and sPecificity contains false Positives in the formulas; see FirstAid):

  • sensitivity = true positive / (true positive + false negative) = 1 - false negative rate --> higher sensitivity means less rate of false negatives
  • specificity = true negative / (true negative + false positive) = 1 - false positive rate --> higher specificity means less rate of false positives

SPIN/SNOUT also helps to remember that specific tests rule in disease, and sensitive tests rule out disease

... anjum made a comment on nbme19/block3/q#16 (13 yo girl grows over the summer; what accounts for increased intestinal absorption of calcium?)
submitted by anjum(22)

7-dehydrocholesterol is a form of pre-vitamin D3 synthesized in the skin from UBV. It is converted to Cholecalciferol, which is the inactive form of Vitamin D3 that is actually in first aid.

kevin  Cholecalciferol is synthesized from 7-dehydrocholesterol by UV, but yes, correct +
i_hate_it_here  Didn't know the products of it were considered hormones my bad i guess +
... metformality made a comment on nbme19/block4/q#17 (60 yo man, 20-year history of hypertension; shortness of breath and fatigue for 3 months)
submitted by metformality(14)
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sThi patenti ihtw a siohtry iccohrn yspinthreneo si otsm lkelyi sgifrnefu morf tfle erath rfaeuil drcee(dsea ircadac up,)ouott asignuc the odblo ot kbca up in eht nlugs (lkCrcsae rea hrdae yt,irllbleaa shtersson fo ba)trhe nad htat gtuirelns tnio eareiscdn redtlfoaa rof teh grhti eids fo eth rta,eh sgianri het rspsuree in eth irhgt areth hbr,amecs hwhci egt sttreitmand cabk to rclante eiv.n

anjum  shortness of breath = Left heart failure +3
cassdawg  The way I approached the question was a little different: I realized it was heart failure and left would cause lung backup and right the venous backup. When addressing the +6
cassdawg  *the question my thinking was CO = HRxSV; in heart failure we are not pumping as much blood so lower SV (and on top of that his HR is not increased and I think the low blood pressure indicates decompensated heart failure) so CO is definitely lowered. Then CVP would have to be increased because that is how we get the edema (and backup into the venous system increases CVP). +1
chaosawaits  @cassdawg, I approached it very similarly. The best immediate indicator that this is cardiogenic shock is the pulse pressure (30 mmHg). Normal PP = 40-60 mmHg. Therefore, you know that CO has been compromised. The edema indicates that CVP (measurement of the venae cavae BP)has increased. +
an1  because this guy has crackles and ankle edema, we know that there is LHF AND RHF respectively. the most common cause of RHF is actually LHF. So crackles mean that fluid is accumulating in the lung. Where will it back up? RV and RA causing increased CVP. Crackles mean LHF, and the the LV isn't working well, the cardiac output will decrease for sure +
... peteandplop made a comment on nbme19/block0/q#0 (80 year old shortness of...)
submitted by peteandplop(38)

The above is correct in terms of MoA, however I believe the stem states it is PT (prothrombin) prolongation, not PTT (Partial Thromboplastin). I did not have any idea what dicumarol was.. but here was my logic:

  1. Patient had aortic valve replacement, she's 80, probably put on an anti-coagulant
  2. I know Warfarin is sold under the brand name Coumadin
  3. Remind yourself that Warfin was discovered in 1927 (10,9,2,7) and inhibits Vit K dependent clotting factors (vit K deficiency-like state)
  4. Pronounce the drug not in FA as diCOUMarol, and you shall hopefully now know it also inhibits epoxide reductase, and pseudo guess your way to victory.
rina  Yes it was PT! Personally I forgot that PT detects changes in I, II (thrombin), V, VII, & X. Vit. K affects II (thrombin), VII, IX & X so there is significant overlap. +
... sh_nu made a comment on nbme19/block1/q#7 (48 yo woman, 2 weeks fever and mucus in stool)
submitted by sh_nu(3)
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hTis Q uocld eb senawder otw yaw,s eno ohhturg iinomeatlin ro gwonikn ohw to fediniyt the l!ceu owN vai oimtnlnaiie . .).A nmayil nsee in DIAS ntspatei ( Q smet does ton trcdie Q that )awC)y lFuo gilemnls eahardri t"f"Dy )at herTe esedn to eb a ritda " esy PEaOeyTHmAgl + eoeelylgap"Smn pksgn"ii "erfve aa"n"ytpcionpe mya aols veha nsik lioevnmtvne E) louf lgsinelm regen gianlva crgdsaehi

)B EULC* UQR IAPN + celur

cbreland  I marked off Entamoeba because I thought it always caused bloody diarrhea... damn +3
aakb  between Giardia and Entamoeba -- giardia doesn't invade intestinal wall but entamoeba does (per sketchy) +
pfebo  Entamoeba: flask-shaped ulcers, Liver abscess +1
... drdoom made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
submitted by drdoom(969)
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siTh is enaysilstle a olafmr olgic tusn.eioq giLlolcya gps,nieka het tnosueiq sska su ot ytdeifni a mismanech taht rumto pospusrsesr heva cwihh se-nnoceootprog do nI roteh s,dorw thwa si a esahnimcm rdhaes yb all nwkon rutmo spsurrssepo tub otn sedrah by ayn nkwon p-toesgoc?nreono For atht oes,anr it โ€™acnt be lipha;rhnptosooy sr,eu phiaplsnoyoothr is a cmaenhsmi of tmoru posusprsers but โ€™sti oasl a emsnmciah fo many nwkon tsogp.o-rceoneno

... cassdawg made a comment on nbme19/block1/q#34 (12 yo girl, 5 days unable to walk but unconcerned)
submitted by cassdawg(1398)

The key to answering this is that she seems unconcerned with her symptoms, which is a hallmark of conversion disorder (la belle indifference) [FA2020 pg 566]

Illness anxiety disorder would be preoccupation with having a certain illness, and inability to be reassured when there are negative findings.

Depersonalization/derealization is a dissociative disorder and "out of body experience" with a feeling of detachment from the body or environment.

Brief psychotic disorder would present more likely with delusions, hallucinations, or some other characteristic of psychosis.

PTSD would present after an extremely traumatic event when symptoms such as anxiety, flashbacks, hyperarousal, and nightmares persist for greater than 1 month after the event.

... ajguard26 made a comment on nbme19/block2/q#13 (25 yo man, exercise test. Most likely physiologic changes)
submitted by ajguard26(41)
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As the sueclm rsokw nda krbesa odnw PT,A idneasoen is dcedr,puo ieadlng ot an nieersac ni het tsu.seis hisT ieecsrdan oanidsene useacs olv,sinaadiot ichhw ni turn iarscnees alcvrsua cectndounca te(h owfl of a emouvl of obold guhtroh teh vu.scauater)l

Agthhoul uyo mya khnit usclem onrociatntc amy edla ot a raseeced ni olwf rghhtuo het ele(svs)s yb sugneeqzi down on ,tmhe hsit hnmaemsci si croevemo by teh sidneacer aardcci pttuou rfom the

rwd1027  ่ฟ™ๆ˜ฏไป€ไนˆ่ฏญ่จ€๏ผŸ +
csalib2  ่ฟ™ไธๆ˜ฏไธ€็ง่ฏญ่จ€ใ€‚ ่ฟ™ๆ˜ฏโ€œไบ‰ๅคบโ€ใ€‚ ๆ‚จๅฟ…้กปไป˜่ดนๆ‰่ƒฝๆŸฅ็œ‹่ฏดๆ˜Žใ€‚ +
... cassdawg made a comment on nbme19/block2/q#17 (Scurvy symptoms associated with decreased activity of which enzyme?)
submitted by cassdawg(1398)

Scurvy is the deficiency in Vitamin C. Vitamin C is necessary for hydroxylation of proline and lysine residues in collagen. Prolyl hydroxylase is responsible for the hydroxylation of proline (see this Wikepedia article)

... blueberriesyum made a comment on nbme19/block2/q#23 (10 yo girl, slightly painful 2 mm subcutaneous nodule on chin)
submitted by blueberriesyum(12)

Presence of multinucleated giant cells surrounding foreign body (staple) shows granuloma.

... cassdawg made a comment on nbme19/block2/q#46 (Decreased pulmonary artery pressure facilitated by increase in the intracellular concentration of which molecule?)
submitted by cassdawg(1398)

This requires knowledge of MOA for phosphodiesterase inhibitors (which are also used for erectile dysfunction). All phosphodiesterase inhibitors will inhibit phosphodiesterase, which normally catalyzes hydrolysis of cAMP or cGMP, so they will work by increasing cAMP/cGMP levels! [FA2020 p246]

NOTE: do not get confused by the addition of NO as an answer, though arteriole dilation by phosphodiesterase inhibitors works in part by enhancing NO activity on smooth muscle, it does not increase the concentration of NO. NO triggers increased cGMP to dilate smooth muscles, and phosphodiesterase inhibitors prevent breakdown of this cGMP, so they work in synergy!

... aliyah made a comment on nbme19/block3/q#5 (30 yo woman, 1 week of visual difficulty)
submitted by aliyah(35)
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Teh ightr yese' fnertfee sernev rae iwk,ngor sa tlef eey tmnlutaoiis csuase a hncaeg in hte htgri ey.heTe hritg eye pcito n. deaagm usecas ti's etfnraef n. to eb meda.dag It c'tan rcray onif to rabni, os igtrh dna eflt eey ncta' ctsnctori to .tglhi

icedcoffeeislyfe  APD--> swinging flashlight test, light in the AFFECTED eye will result in dilation of both pupils inappropriately +1
cbay0509  thank you +
chaosawaits  But if right optic nerve doesn't work, why does it dilate normally in the dark to 6 mm? +
pakimd  @nbme_123 im not sure if im correct but i think the reason why right edinger westphal nucleus is not the correct answer is because the left edinger westphal nucleus sends one axon to the right edinger westphal nucleus and one to right pretectal nucleus so that way damage to right edinger westphal will still result in relaying of efferent innervation to the right eye +
... wherearetheanswers made a comment on nbme19/block3/q#39 (45 yo man, lost outdoors in the Rocky Mountains for 10 days)
submitted by wherearetheanswers(12)

The kidneys make glucose too? 6 years of studying science and no one mentions the kidneys.

... peteandplop made a comment on nbme19/block3/q#39 (45 yo man, lost outdoors in the Rocky Mountains for 10 days)
submitted by peteandplop(38)

While not traditionally discussed, the kidneys' contributions to maintaining glucose homeostasis are significant and include such functions as release of glucose into the circulation via gluconeogenesis, uptake of glucose from the circulation to satisfy their energy needs, and reabsorption of glucose at the level of the proximal tubule.

FA2019 p78 - [Gluconeogensis] occurs primarily in the liver; serves to maintain euglycemia during fasting. Enzymes also found in kidney, intestinal epithelium.

... seems like a silly thing to test... shrugs shoulders laughs in NBME

shieldmaiden  especially silly since they also list the small and the large intestine +1
... the_enigma28 made a comment on nbme19/block3/q#40 (25 yo woman requests prenatal diagnosis at 12 weeks gestation)
submitted by the_enigma28(55)

Amniotic fluid phospholipid analysis is used for testing fetal lung maturity via measuring surfactant production.

Fetal echocardiography would reveal any congenital heart defects if present, but would not be diagnostic of Downs syndrome

Fetal ultrasound First-trimester ultrasound commonly shows increased nuchal translucency and hypoplastic nasal bone. But I feel this is used more commonly in older women who might have chromosomal dysgenesis as the cause of downs syndrome

Fetal biopsy Pretty invasive technique, when we have a lesser invasive and more specific test available.

drdoom  [system mailer] your account has been upgraded: FORMAT NINJA +
... wherearetheanswers made a comment on nbme19/block3/q#49 (Schematic representation of eukaryotic translation)
submitted by wherearetheanswers(12)

Another tRNA has to attach to the A site before the peptide chain can be hydrolyzed from the P site and moved to the A site tRNA (FA 2020 pg 45)

fataldose  As the Peptide chain is transfered to the tRNA at the A site, the ribosome moves down the mRNA moving the now empty P site tRNA to the E site, and the tRNA from the A site to the P site, making room for the next amino acid charged tRNA to attach to the A site. Additional points- The translation comes to an end when a releasing factor recognizes one of the stop codons (does not code for an amino acid), which then catalyzes the release of the peptide chain from the tRNA in the P site. Peptidyl transfer to E site is wrong because peptidyl tranfer occurs between P site to the A site, not to the E site eIF4E is a eukaryotic translation initiation factor involved in directing ribosomes to the cap structure of mRNAs. Once methionine charged tRNA locates the start codon, all initiation factors are released. +7
... cbay0509 made a comment on nbme19/block4/q#15 (60 yo woman, 1 year of episodic involuntary rhythmic jerking of R leg and foot; brain MRI reveals 2 cm round enhancing lesion within interhemispheric fissure)
submitted by cbay0509(6)

the hallmark of meningioma is its relation to a meningeal surface hence relation to sulcus

cbreland  I really wanted to pick GBM/astrocytoma here +
... cassdawg made a comment on nbme19/block4/q#46 (24 yo woman; renal oxygen consumption found to be 20 mL per minute; which process consumes the most oxygen?)
submitted by cassdawg(1398)

I am assuming this is just something we are expected to know; tubular reabsorption requires the most oxygen because it would consume the most ATP out of the processes in the kidney?

waitingonprometric  I believe this is correct--assuming that active transport of solutes at the thick ascending limb and active transport of solutes (secondary to Na/K pump) at the PCT consumes O2 at highest rate b/c of ATP use. Since tubular reabsorption always happening...very high use of O2 relative to the other answer choices that occur sporadically in response to body homeostatic changes? Note: glomerular filtration is always happening, but that's passive movement through fenestrated capillaries (i.e. no ATP used). +3
hiroshimi  Also, PCT and thick ascending tubule are the two areas that are most susceptible to hypoxic injury in the kidneys. +4
... cassdawg made a comment on nbme19/block0/q#0 (A 27-year-old woman has an episode of pneumococcal...)
submitted by cassdawg(1398)

Penicillin can cause a direct Coombs + autoimmune hemolytic anemia

The Direct Coomb's test involves anti-Ig antibody (Coombs reagent) added to patientโ€™s RBCs. RBCs agglutinate if the RBCs are already coated with antibodies (indicating that the body is making antibodies that bind the RBCs). RBCs tagged with antibodies are destroyed in the spleen. Penicillin is thought to act as a hapten binding with proteins on the RBCs and triggering an antibody response against the penicillin-RBC complex [FA2020 p423]

cbreland  To add, LDH would be increased with many types of hemolytic anemia. Not be the best answer, not as specific +
kevin  Penicillins and cephalosporins act as haptens, alpha-methyldopa causes direct Abs against self Ag on RBC. - Dr. Sattar +3
... jp1003 made a comment on nbme19/block0/q#0 (Investigator studying spermatogenesis...tight...)
submitted by jp1003(9)

FA pg614

tight junctions between adjacent sertoli cells form blood-testis barrier--> isolate gametes from autoimmune attacks

mannan  FA2020 pg 628 +1
... brasel made a comment on nbme19/block0/q#0 (A 30-year-old man develops urinary incontinence 2 weeks)
submitted by brasel(16)

Overflow incontinence is present (bladder fills then leaks slightly), so either:

1.) something blocking outflow (e.g.; BPH)

2.) impaired contraction of bladder (e.g.; damaged nerves)

Only the pelvic nerve causes detrusor contraction, so it is the only possible answer. External sphincter, pudendal nerve, and skeletal muscle all does the same thing. Hypogastric nerve helps retain urine (relaxes detrusor) so it is clearly not damaged.

solidshake  I agree answer is the parasympathetic Pelvic Splanchnic nerve, but don't forget there are 2 mechanisms that are affected when it's damaged: 1. Impaired involuntary contraction of bladder and also 2. Impaired involuntary relaxation of the internal urethral sphincter. Pelvic Splanchnic nerve facilitates both of those + voluntary somatic relaxation of external urethral sphincter via pudendal nerve allows you to pee +
chaosawaits  @solidshake I may be just unable to search properly, but I found the internal urethral sphincter to be innervated by the sympathetic fibers from T10-L2 through the inferior hypogastric plexus (source: Wikipedia) Urination occurs by preganglionic inhibition of the sympathetic fibers via descending reticulospinal tract. Fact check appreciated. +1
... cassdawg made a comment on nbme19/block1/q#16 (60 yo man, 2 weeks flank pain and blood in urine)
submitted by cassdawg(1398)

TL;DR: Renal cell carcinoma can present with polycythemia (due to increased erythropoietin) and hypercalcemia (due to PTHrP) [FA2020 p228]

So the question is what is the primary cancer? He has two tumor locations (kidney and lungs), which could be primary or from metastases.

I narrowed it down to metastatic renal cell carcinoma and bronchogenic squamous cell carcinoma (see below). The only other infoemation really given that could allow us to distinguish is the lab values indicating paraneoplastic syndromes. These are both known to cause paraneoplastic syndromes which can cause hypercalcemia. So focusing on the polycythemia, this is more specific for renal cell carcinoma because no lung cancer secretes EPO.

I eliminated undifferentiated carcinoma because it is too nonspecific and metastatic transitional cell carcinoma because it is rare in the kidney (with no paraneoplastic syndrome typically associated which could cause the lab abnormalities) and there is no mention of bladder.

Multiple myeloma can have renal involvement but does not typically involve the lungs and would present with bone lytic lesions and anemia rather than polycythemia. [FA2020 p431]

... cassdawg made a comment on nbme19/block1/q#31 (32 yo man on primaquine)
submitted by cassdawg(1398)

This is G6PD deficiency. (FA2020 p422)

G6PD deficiency causes a hemolytic anemia when individuals are exposed to antimalarials due to the increased oxidative stress. This is due to the deficiency in replenishing NADPH which is necessary to replinish reduced glutathione which aids in quenching free radicals.

cbay0509  thank you +1
... cassdawg made a comment on nbme19/block2/q#9 (Lab findings expected after administration of insulin and saline)
submitted by cassdawg(1398)

The first thing to look at is potassium, which would decrease because insulin facilitates intracellular shift of potassium (which is why it is used as a treatment for hyperkalemia!). This leaves only two potential answers!

The next thing I immediately noticed was that our patient's labs indicated anion gap metabolic acidosis (likely due to diabetic ketoacidosis). Administration of insulin would improve this condition, and one of the main things that would occur is correction of acidosis, so pH would increase. The other parts of the answer also make sense, as bicarbonate begins to return to normal with the increase in pH and less necessity for use in buffering, BUN decreases as the kidney damage occurring can be mostly reversed, and blood CO2 increases because there is no longer the need for respiratory compensation of the metabolic acidosis.