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NBME 19 Answers

Block/Question (21.8 difficulty score)
53 yo woman w/GERD. Diet change, stress ...

Block/Question (28.2 difficulty score)
66 yo man, 2 months of not being able to ...
Libido: decreased; Noctural erections: normalπŸ”

Block/Question (9.8 difficulty score)
48 yo woman, 2 weeks of fever and stool with ...
Entamoeba histolyticaπŸ”

Block/Question (14.8 difficulty score)
What mechanism of action do tumor-suppressor ...
Inhibition of cell-cycle regulationπŸ”

Block/Question (5.8 difficulty score)
60 yo man, 2 week history of flank pain and ...
Metastatic renal cell carcinomaπŸ”

Block/Question (13.2 difficulty score)
29 yo man with untreated HIV infection; what ...
CD8+ T lymphocyte–mediated killingπŸ”

Block/Question (12.2 difficulty score)
62 yo woman with sudden weakness of left leg; ...
Right anterior cerebral arteryπŸ”

Block/Question (12.5 difficulty score)
Niemann-Pick disease is characterized by ...
Decreased lysosomal hydrolase activityπŸ”

Block/Question (5.2 difficulty score)
13 yo girl with mother for routine visit; ...
Ask mother to leave the room before asking the patient any questions.πŸ”

Block/Question (5.9 difficulty score)
32 yo man given primaquine for malaria ...
Enzyme deficiency in the erythrocytesπŸ”

Block/Question (5.3 difficulty score)
12 yo girl unable to walk for 5 days but is ...
Conversion disorderπŸ”

Block/Question (30.0 difficulty score)
5 yo boy, R eye pain for 1 week; retinal exam ...
Retinal cellsπŸ”

Block/Question (4.3 difficulty score)
36 yo woman presents to ED after believing ...
Panic disorderπŸ”

Block/Question (10.4 difficulty score)
What advantage does randomized controlled ...
Better control for confounding variablesπŸ”

Block/Question (5.9 difficulty score)
Three tests are developed to identify ...
Test 3 followed by test 1 if test 3 is positiveπŸ”

Block/Question (8.8 difficulty score)
62 yo man, right-handed, suffers decreased ...
Area labeled by letter 'A'πŸ”

Block/Question (6.5 difficulty score)
38 yo woman, 6 months depressed mood, joint ...
Lyme diseaseπŸ”

Block/Question (5.2 difficulty score)
24 yo man, generalized tonic-clonic seizure; ...
Psychogenic polydipsiaπŸ”

Block/Question (6.7 difficulty score)
Retinoic acid receptors and HOX gene products ...
Transcription factorsπŸ”

Block/Question (5.1 difficulty score)
Lab findings expected after administration of ...
Potassium decreased; Bicarbonate increased; BUN decreased; Arterial pH increased; blood CO2 increasedπŸ”

Block/Question (18.1 difficulty score)
40 yo woman, chorionic villus sampling
Confined placental mosaicismπŸ”

Block/Question (5.5 difficulty score)
Scurvy symptoms associated with decreased ...
Prolyl hydroxylaseπŸ”

Block/Question (10.1 difficulty score)
10 yo girl, slightly painful 2 mm ...

Block/Question (8.1 difficulty score)
48 yo woman, 3 months fatigue; X-rays reveal ...
Paracrine stimulation of osteoclasts by osteoblastsπŸ”

Block/Question (5.1 difficulty score)
Case-control study; 95 percent confidence ...
The likelihood is 95% that the true value for the odds ratio is between [the reported range]πŸ”

Block/Question (4.0 difficulty score)
Mechanism by which action potentials permit ...
Transmission along T tubulesπŸ”

Block/Question (5.0 difficulty score)
75 yo man with dementia; no advanced directives
Encourage the family to come to a consensus based on their perception of the patient's wishesπŸ”

Block/Question (5.4 difficulty score)
2 day old newborn with jaundice
Conjugation of bilirubin to glucuronic acidπŸ”

Block/Question (4.7 difficulty score)
45 yo woman undergoing vinblastine chemotherapy
Decreased number of neutrophilsπŸ”

Block/Question (7.8 difficulty score)
Pathway of the transepithelial transport of water
Pathway denoted by letter 'C'πŸ”

Block/Question (5.2 difficulty score)
Decreased pulmonary artery pressure ...

Block/Question (11.9 difficulty score)
30 yo woman, 1 week of visual difficulty
Right optic nerveπŸ”

Block/Question (7.2 difficulty score)
Cells most responsible for graft rejection?
T lymphocytesπŸ”

Block/Question (13.3 difficulty score)
23 yo woman engages in 30 minutes of ...
Increased, as a result of distention and recruitment of microvesselsπŸ”

Block/Question (9.9 difficulty score)
13 yo girl grows over the summer; what ...
Hormones derived from 7-dehydrocholesterolπŸ”

Block/Question (8.6 difficulty score)
45 yo patient, chronic alcohol dependence, ...
Chest radiograph labeled 'D'πŸ”

Block/Question (13.3 difficulty score)
30 yo man and 24 yo woman; best estimate that ...
1 in 600πŸ”

Block/Question (8.2 difficulty score)
Blood gas values: arterial O<sub>2</sub> ...

Block/Question (7.4 difficulty score)
74 yo man; continuous systolic-diastolic ...
Renal artery stenosisπŸ”

Block/Question (7.8 difficulty score)
40 yo man, 1 month increasing malaise, ...

Block/Question (6.6 difficulty score)
15 yo girl receives bone marrow transplant; ...
Nonautologous donorπŸ”

Block/Question (4.9 difficulty score)
19 yo man stabbed in abdomen; has been ...
Antisocial personality disorderπŸ”

Block/Question (8.0 difficulty score)
52 yo man, 4 hours of severe headache, ...
Increased total peripheral resistance and decreased cardiac outputπŸ”

Block/Question (8.9 difficulty score)
45 yo man, lost outdoors in the Rocky ...

Block/Question (11.3 difficulty score)
25 yo woman requests prenatal diagnosis at 12 ...
Chorionic villi samplingπŸ”

Block/Question (8.3 difficulty score)
41 yo woman, 34 weeks gestation; ...
Decreased functional residual capacityπŸ”

Block/Question (13.5 difficulty score)
Study conducted to determine effects of drug ...

Block/Question (7.0 difficulty score)
52 yo man, sudden onset of substernal chest pain

Block/Question (9.2 difficulty score)
Schematic representation of eukaryotic translation
Binding of aminoacyl-tRNA to the A siteπŸ”

Block/Question (8.2 difficulty score)
39 yo man, 6 months of headache, muscle ...
Basophilic stipplingπŸ”

Block/Question (4.3 difficulty score)
26 yo woman after jejunoileal bypass for ...
Vitamin AπŸ”

Block/Question (5.3 difficulty score)
11 yo boy, right mid-thigh pain for 2 weeks; ...
Ewing sarcomaπŸ”

Block/Question (6.5 difficulty score)
60 yo woman, 1 year of episodic involuntary ...

Block/Question (8.2 difficulty score)
60 yo man, 20-year history of hypertension; ...
Cardiac output: decreased; CVP: increasedπŸ”

Block/Question (7.9 difficulty score)
54 yo man, routine exam; given an angiotensin ...
Area labeled by letter 'F' (efferent arteriole)πŸ”

Block/Question (5.7 difficulty score)
52 yo woman prescribed cisplatin for ...

Block/Question (9.6 difficulty score)
Oral fluid therapy for diarrhea caused by ...
Membrane transport mechanism denoted by letter 'C' (Sodium-Glucose cotransporter)πŸ”

Block/Question (10.7 difficulty score)
24 yo woman; renal oxygen consumption found ...
Tubular reabsorptionπŸ”

Block/Question (5.2 difficulty score)
30 yo woman with high-grade intraepithelial lesion
Superficial to the basement membraneπŸ”

Block/Question (7.1 difficulty score)
A 27-year-old woman has an episode of ...
Direct antiglobulin (Coombs) testπŸ”

Block/Question (10.5 difficulty score)
During an experiment, an isolated skeletal ...

Block/Question (4.4 difficulty score)
A newborn delivered at term to a ...

clotting moa
Block/Question (3.9 difficulty score)
80 year old shortness of ...
Induces a vitamin K deficiency-like stateπŸ”

Block/Question (2.6 difficulty score)
A 43-year-old woman...aspirin...most likely ...
"B" step converting arachidonic acid to prostaglandin G2πŸ”

Block/Question (2.9 difficulty score)
48-year-old man admitted for idiopathic ...
Right ventricular afterloadπŸ”

Block/Question (3.4 difficulty score)
Investigator studying spermatogenesis...tight ...

Block/Question (3.6 difficulty score)
23-year-old woman...heparin...decreased ...
Antiplatelet antibodiesπŸ”

Block/Question (5.0 difficulty score)
76-year-old-man...severe substernal chest ...
Coronary vasospasm due to alpha1-adrenergic stimulationπŸ”

Block/Question (5.6 difficulty score)
Graph shows rate of breakdown of skeletal ...
Allosteric activatorπŸ”

Block/Question (2.6 difficulty score)
During an experiment, a researcher blocks the ...
Retrograde axonal transportπŸ”

Block/Question (1.7 difficulty score)
Investigator does an experiment... third ...

Block/Question (2.6 difficulty score)
A 2-year-old boy with cerebral palsy is ...

Block/Question (2.3 difficulty score)
An 11-year-old boy has repeated episodes of ...
NADPH oxidaseπŸ”

Block/Question (4.2 difficulty score)
An investigator studying the function of a ...
decreases the amplitude of the action potentialπŸ”

Block/Question (4.0 difficulty score)
A 35-year-old man comes to the physician to ...

Block/Question (5.0 difficulty score)
A 30-year-old man develops urinary ...
pelvic nervesπŸ”

Block/Question (7.1 difficulty score)
A 70-year-old man develops a progressive ...
Frontal lobe disinhibitionπŸ”

Block/Question (5.1 difficulty score)
Immediately after cerebral infarction, a ...
A (Broca's area)πŸ”

Block/Question (4.0 difficulty score)
In the diagram of the proximal renal tubular ...
C (no carriers, going from lumen to basolateral side)πŸ”

FA19p490 stroke neuro
Block/Question (3.2 difficulty score)
A 33-year-old woman has had weakness of the ...
C (face portion - MCA - of primary motor homonculus) πŸ”

Block/Question (1.1 difficulty score)
Naive mouse thymocyte precursors are obtained ...
Decreased cell death in the thymic cortex πŸ”

Block/Question (0.2 difficulty score)
a 73 yo man comes to the physician because of ...
calcium: no change, phosphorus: no change, alk phos increase, pth no change. πŸ”

Block/Question (0.1 difficulty score)
A 22-year-old man get separate from a group ...
Area postremaπŸ”

Block/Question (0.1 difficulty score)
A 62-year-old woman has an abdominal aortic ...
Cholesterol emboliπŸ”

Block/Question (0.1 difficulty score)
A 25-year-old man has significant blood loss ...
Reabsorption of fluid into systemic capillaries πŸ”

Recent comments ...

... aliyah made a comment on nbme19/block1/q#35 (5 yo boy, right eye pain 1 week)
submitted by aliyah(25)
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fI a merg lcle or oitmcas clel dha eth logranii nttmou,ia hetn e'rhtes an rsecdiane rski orf cecarn in ohetr atsrp of teh doby Io.tof lyno iealtrn sclel in eon yee is tdmute,a lnoy atht noe eey is ta skri fro

i_hate_it_here  Gotta love that I can't even review the free contribution you put up. Thanks nbme answers guy +
... ajguard26 made a comment on nbme19/block1/q#1 (53 yo woman with GERD.)
submitted by ajguard26(30)
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So ahtlough otlMsoorisp DEOS recinesa suucm cdnuopoitr and is vrto-estprigctoea d(na ni FA sdeo taets ttha ti sedarcese idca pndt)ocuio,r hyetreb raiscneedg topssymm nda ngaiid ni age,hlni zmopelorea is het "meor crtorce" coec.ih isTh si ebcaues peomerolza si a rtpopp-oumn intobii,hr iwhhc wlil tca eylitrcd on hte noptor upmsp fo eht mosthca nad eseraedc the iodnfnfeg tenag omer naht eht tlmiooosspr ilw.l eor,ehTefr it si teh rstfi nlei drug ofr .GRDE

... ajguard26 made a comment on nbme19/block2/q#16 (40 yo woman, chorionic villus sampling)
submitted by ajguard26(30)
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roiCcihno ivlil mangilps si eht tikagn of etegcin lateraim iwntih in het rcoionich vilil of teh tpac.elan oociCirnh nagmlsip si ndeo nhwe a npeiatt is ta gihh rski ofr achmomolosr nrmaseilaoibt orvisp(eu pso. stes,t o35y ro drl,oe fmylai .)hx ngridu the 103-1 ekwes fo naenr.ycgp

dnoeCfin lpcanleat mosmcsaii trsuels enhw eth ...CSV gnittse ocmse back kbac shginow a oirmys,t tbu lla nsutubqsee isetngt nd(a eht ustef elfits) heva anlrmo comsolhmrao .cnsuot iThs aym eb deu ot eierht a oiabtctplhrso itm,oantu or yb t"omrcsii erc,"seu ni whchi srotmici slcel atth ewre dsoeppus ot eb in hte utsef aer cneonfdi to eth cntaepla ot nevtrpe na amlrbona e.fstu

cbay0509  thank you +
... aliyah made a comment on nbme19/block1/q#17 (29 yo man untreated HIV)
submitted by aliyah(25)
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terfA eth +4DC eclsl ceembo tdefc,nie eth C+8D sllce llki hmet.

cbreland  Same for the macrophages and dendritic cells that would be infected. Intracellular pathogen that would need to have CD8 T cell mediated death +
... 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(924)

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! +
... peteandplop made a comment on nbme19/block0/q#0 (76-year-old-man...severe substernal chest...)
submitted by peteandplop(22)

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
... drdoom made a comment on nbme19/block1/q#4 (66 yo man, 2 months no erection)
submitted by drdoom(801)
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lIanbiiyt to ntnaimai na eerioctn = tieerlec uytniosfcnd. oS now eht oueqnsti is ?"hWy"

iFegatu, ducitflfiy ielgsnep, yitdfcluif ginotcantercn si iatrgsnt ot ndsuo lkie sdirpeneos. ylucf"iDift crn"toanncietg thgmi eb rpitteeendr as eraimpdi ivxteueec ntufnoic ro the niningesgb of arse-ulaactrvdle mneidaet da(eeitmn dterlae ot lamsl btu onuurmse arleberc i,tcnfsra) but on epSt 1 imeadent illw eb nbtltaa ,( "tlos ish ywa eo,"hm w""igean,nrd c.).et

soeprDisen si tyaucall nmoomc trfea a dngiitbielat tneev ielk o,rekts as oyu hgmit xpcet.e hWti inoeserpds cosme a slso fo aeusxl irntetes dan eitβ€”dheatrs si eesdcaedr ldiibo.

nOe nca ekam teh meartgun hatt a "luarcasv "aptenit hmigt ehav seom isuses wiht ihs sp"eip" aritseos(roielr,sc amiiascraeyym/htspphttaptec tuinfsyod)cn d,na ofr hits nsreo,a nocnrulta cierteon dolhsu eb eerdecdas; but neot ttah hnignto is endoiemnt tuoba sdggniann-tlo rsvauacl dsasiee (no hx fo en)pieohnsr.ty

sA a lu,erst hte sbte wresan oceich hree si C. bdoi(iL eedacrsde btu trnuaonlc eseotnirc n.rml)oa hTe igb onieustq I have i,s woh eht eckh dseo tish guy wonk e'sh rdha nehw 'hse lsaep?!!e 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 +9
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 (S2–S4)! a β€œbrain stroke” (UMN damage or β€œcortical damage”) would not kill your ability to have nocturnal erections! +
djeffs1  in the versions I purchased from them they highlight the correct answer in the test review +
... 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(11)
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eScni teh arf'thes ibligsn si fce,adetf ew wnok thta teh aer'thsf taerpsn ear htob racresir. htaT neams het ibpslseo onepsgtye fo het ahrtfe rea A,A aA, ,Aa or aa.

We owkn teh ehfatr is dneate,ffcu so htat easnm eh ntnoca eb ,aa and utsm eb hirete A,A Aa, or .Aa

ecSin eethr ear nloy 3 inefedfrt npeyetosg he doclu vhe,a ithw 2 of etmh enibg creairr otyes,pnge rhtee si a 23/ briylaipotb he is a ecir.rar

So we nbotia hte pblibtyriao of teh tfearh gpaniss no a csriveees leella sa 23/ (iibtpyorlba of ngibe a rrari)ec x 1/2 atlipro(biby fo sngsipa on a vseeisrce lelael fi he si a ).arcerir heT /32 is not atrvnlee ot hte poliiyatbbr that eth moethr is a cirea.rr

We oknw eth uefcrqeny of afcetdfe asdiidnviul ni het noupoltiap at grale si /,001400 ,^q(=2) os 0q/=12.0

=,q1+P os /00192=9p adn p202q0/)9=1(02/2)0(91.

oT amke ulpltnmictaiio eiears ew asuesm ,21=/90091 s:o

002(q12/=0p211/)=*0 -g;-t& hits si het arcrier ueqrfyecn ..ak.a,( rhost)eoetegyz ni hte pua,itlpoon ichhw we anc muases fro het eomrht.

,So to neswra eth ireten enuositq ew iullptym het bpyrltiiabo hatt fteahr si a raerrci )/23( dan essspa on the lelael 2(/1) meist teh rlitobyipab ttha mhreot is a reirrac 1)010(/ nda ssspae on hte lleael 2()/1; igtptnu it lla oghtetre we h:aev

/3(11)*1))1)22(/(**/0/20( = 102/20 = 0/610

cbay0509  thank you +
... cassdawg made a comment on nbme19/block3/q#17 (45 yo patient, chronic alcohol dependence, foul-smelling brownish sputum)
submitted by cassdawg(924)

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.

... cassdawg made a comment on nbme19/block4/q#33 (Oral fluid therapy for diarrhea caused by <i>Vibrio cholerae</i>)
submitted by cassdawg(924)

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! +
... ajguard26 made a comment on nbme19/block1/q#24 (62 yo woman sudden weakness of left leg)
submitted by ajguard26(30)
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hisT tnpaeti srespetn wthi csiacls purep ootrm ournne ileons pmsys:omt wsesek,an y,rieraeexhlfp nad rcesddeea neissaton. orHvew,e het ontseqiu tsaste ehs n"ncato llte erwhteh her eftl atger teo si drsiea ro sdedspe"re wehn her yees rea oldes,c wihch amy emak oyu irecndorse adn think htree yam eb eoms erpvoicpirtoep ssusie ythe ear yrngit ot ithn .at hsTi si tno eht csea. Elspcyaile noec ethy onteinm eehrt rae on otrhe ieabiomaltnsr i.,.(e on urpep lmib iaratmnioelsb ro irhtg eddsi btmio)aesairl.n If thsi si teh ,asec hetre is no adaemg to het castrt at lal hwc(ih ear ilslt dnodsrieec )MU.N

hofee,Trre eht aadgme si yrlupe omotr adn rssyoen ni het etfl gel, hwich si on the aliedm sapect fo the afrlton and ltarapie eoslb vlersice.eytp isTh aera is dplispeu yb the nrarotei bacreler rt.yaer

issamd1221  contralateral deficits +
cbay0509  thank you +
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 +
... cassdawg made a comment on nbme19/block2/q#25 (48 yo woman, 3 months fatigue; X-rays reveal generalized osteopenia)
submitted by cassdawg(924)

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#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(924)

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) +
... 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(924)

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. +2
... 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(924)

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 +
... metformality made a comment on nbme19/block0/q#0 (Isolated skeletal muscle contracted with electrical stimulation)
submitted by metformality(12)
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eWhn a esculm ursn uto fo ulef e(g, seocgu)l dra/no cinpugrod essl TPA nad asβ€œrce”inde lcnaaomciutu of tsoiabtmlee lla( htreo stoiopn esdsbei hte crcteor ,hoceci) it si a sngi of soetn fo lmsuec .utaigfe The tmse is ngkais hwihc of eth filwgoonl lliw a,e”rs?β€œdece nad ti si teh Hp hatt lwil sadceeer ssia(c)iod eud to eht umaotlccuina of clcait aidc membere(r ycslsogiyl wayhpta werhe avurypet gset edoetrvcn to ciatlc a).icd

... blueberriesyum made a comment on nbme19/block0/q#0 (A 70-year-old man develops a progressive disinhibiton)
submitted by blueberriesyum(8)

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 +5
... cassdawg made a comment on nbme19/block1/q#26 (Niemann-Pick)
submitted by cassdawg(924)

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

... 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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sihT is htaw is known sa a iocsmta otntuima: a oinmtatu ttha uosccr ni gnnniloe-mre lselc dn,a foe,reetrh yonl ffsecte guerhadt clesl edierdv ofrm het rntape lecl iwht eth ottuiam.n So, a nmoutiat curroecd ni a tfetderdianefi aetrnp clle ahtt avge reis ot a ste fo ahredgtu llecs ,ich(wh ni tish eca,s erwe idntesde to oeebcm italenr )sstuie.

... metformality made a comment on nbme19/block3/q#12 (23 yo woman engages in 30 minutes of strenuous exercise)
submitted by metformality(12)
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giHh craadci ttuupo ot the alnrmoypu aciuitrncol gudirn ceeisxre iwll esuca teh iietonnssd dan cretrunemti of vsoimleecss nad ahtt lwdou cuaes the snarecei ni ttalo ssoaiocrsctnle- area.

reHe rae otw esmiga ttah srtautlile hist pincprile incyl:e

... 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(924)

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. +1
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). +1
... peteandplop made a comment on nbme19/block0/q#0 (80 year old shortness of...)
submitted by peteandplop(22)

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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iThs Q dculo be nsewaedr wot a,wsy noe htrough iaeiimotnnl or kinwngo woh to yifntdie the el!uc Now iav elntmniaioi ..A.) ymlnai nsee in IDSA tisptaen ( Q etms edso not etcidr Q ttah w) a)yC uFlo mngilsel rdhaiaer ty a"f")Dt reehT sndee ot be a tdiar " eys yagelPEHmTOA + eSngeo"ayepllm pgkiisn" e"vref "ayniptponcae" yam osla ehva isnk nmlveevoitn E) ulfo lleimgns eenrg gaalvin hciegdrsa

)B CE*LU QUR APIN + celru

cbreland  I marked off Entamoeba because I thought it always caused bloody diarrhea... damn +1
aakb  between Giardia and Entamoeba -- giardia doesn't invade intestinal wall but entamoeba does (per sketchy) +
pfebo  Entamoeba: flask-shaped ulcers, Liver abscess +
... picodemolar made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
submitted by picodemolar(3)
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gnenosOec iwht agin of nionufct uantmtoi dael to nsceidear cnpisatt,rroni ct,.e haserew muort speopusrrs ensge bkloc ;-S&tG1-g h.easp N1F enge ptodurc has SAR eaTsGP tiyiacvt whchi ksowr by nophoahitglrpys nad vinactatgi enriotp u)nmifib.(eronor oS erteh is ta lstea 1 omrut srrospuesp egen that okwrs houthrg n.hpiolytrhaopos

... drdoom made a comment on nbme19/block1/q#13 (Mechanism of action of tumor suppressor genes)
submitted by drdoom(801)
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isTh is yseilnsteal a ormlaf ilgoc snuq.ioet oilaLycgl ,paiekgns the euqostni ksas su ot idyeitfn a aisenhcmm taht turom sspusropsre aevh chihw opntrgosooeenc- od on.t nI oerht ,odwsr what si a nsmhemiac hardes yb lal nknow orumt epsrsusprso tbu not ehsdra by nya knnow octone?n-sprgeoo Fro hatt esoan,r it tan’c be ntiypah;lsohoopr ,resu yapitlhhorosnop is a smmichane fo utrmo pssorrespus tbu ist’ aosl a mascmenih fo aymn nnowk eegcnpoo.onsr-ot

... ajguard26 made a comment on nbme19/block1/q#42 (Advantage of randomized controlled studies)
submitted by ajguard26(30)
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ndignouCnfo" "lbieasrva rhee enmsa fn"nuoonigcd b,"isa sieea.nstlyl And sith si tuer sabeeuc a cpspevreoit rohoct oslko ta a ciipesfc eexospur to a besuctnsa vnniealmrtno(e ,onixt u,rdg ce,.)t nad kssa h"Wo llwi lopevde this eisseda if x"oe?dpse sPS'C kloo ttaeptm ot infd a artelevi kris csesaaotid ithw na xsruoe.ep ehyT do nto akte noit unaotcc the ftcsefa rothe .exsuoersp ihTs is oury nuofidnocng i.abs AF gseiv the elaepmx of fdoonnicngu bsai as rmaPlu"yno eeissad si mero nmcmoo in skowerr ni a loca min;e ewerho,v ensmri are mero elkiyl ot k"meos, nad ecisn smkgino anc alos aled to nuamloypr edessa,i uyo n'cta yrlela say heethrw eht snigkom tifs(r or nsodce ah)dn ro eht lcao udts cueass eht per.olbm A callniic r,tail on hte htroe nhad, ascnntoi a stet rougp dna a nctorol ,ruogp so eblasiarv hcsu as eht onifnudgnoc ilabaevr emennidto veboa aer iie.mtdl

... cassdawg made a comment on nbme19/block1/q#44 (Best testing strategy when treatment has serious side effects)
submitted by cassdawg(924)

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

... cassdawg made a comment on nbme19/block2/q#17 (Scurvy symptoms associated with decreased activity of which enzyme?)
submitted by cassdawg(924)

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)

... 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(924)

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(25)
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hTe tirgh 'eesy ffteeenr rsenev rae kgi,worn as elft yee tmisoanilut eascsu a ngaech ni eth ithgr hye.eeT itghr eey tcpio n. maaged acsuse 'tsi fteneafr .n ot eb agdema.d It 'tnac rcyra ionf to ,abnri so rhigt dna flte eey a'tcn nttiorcsc to hlit.g

icedcoffeeislyfe  APD--> swinging flashlight test, light in the AFFECTED eye will result in dilation of both pupils inappropriately +1
cbay0509  thank you +
... 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(15)

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 +
... shadowbox made a comment on nbme19/block3/q#40 (25 yo woman requests prenatal diagnosis at 12 weeks gestation)
submitted by shadowbox(11)
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ehT mest etsats thta the rtmhoe is 21 wseek CSV si fperrmedo s1t treteis,mr uasluly t/b 0-141 ekwes sgentioat ognrdcaci to e-Dp-att.oU Amino si mpeorfedr ertfa 15 ewsk.e Frmo tteDa:-p-Uo etsβ€œAeiscinmno oldhsu eb ferdpmoer refta 51 wskee of nittgosae euseacb eerlair sprecedour rea sels yellki ot eb uf,usecscls ear osseaaditc ihwt eghrhi retsa fo lelc lcuutre r,liuafe and ryarc eargter tfeal ”

... wherearetheanswers made a comment on nbme19/block3/q#49 (Schematic representation of eukaryotic translation)
submitted by wherearetheanswers(10)

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. +4
... 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(12)
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hiTs tptiena ihtw a ohrsyti ihcrcno rnptinsyoeeh is stom ilyekl ifufgrnse frmo felt aetrh ilfauer ereadde(sc adcaric tu,ou)top ngicusa eht obldo to back up ni eth gsnul (realkcCs rae eadhr ,ellatrbyila ehnssrsot of abh)ert nda taht nrsgltuei tino dnrceisea rtafleoda orf the tihrg esid fo het ,aerth nagirsi eht purseser ni eht ihgrt hrate hcr,mbase whihc gte tsdaenirtmt abck ot cltenra

anjum  shortness of breath = Left heart failure +2
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 +4
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). +
... cassdawg made a comment on nbme19/block0/q#0 (A 27-year-old woman has an episode of pneumococcal...)
submitted by cassdawg(924)

Penicillin can cause a direct Coombs + autoimmune hemolytic anemia

The Direct Coomb's test involves anti-Ig antibody (Coombs reagent) added to patient’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 +1
... jp1003 made a comment on nbme19/block0/q#0 (Investigator studying spermatogenesis...tight...)
submitted by jp1003(6)

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(10)

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 +
... cassdawg made a comment on nbme19/block1/q#31 (32 yo man on primaquine)
submitted by cassdawg(924)

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 +
... cassdawg made a comment on nbme19/block1/q#34 (12 yo girl, 5 days unable to walk but unconcerned)
submitted by cassdawg(924)

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.

... cassdawg made a comment on nbme19/block2/q#9 (Lab findings expected after administration of insulin and saline)
submitted by cassdawg(924)

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.

... blueberriesyum made a comment on nbme19/block2/q#23 (10 yo girl, slightly painful 2 mm subcutaneous nodule on chin)
submitted by blueberriesyum(8)

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

... cassdawg made a comment on nbme19/block3/q#9 (Cells most responsible for graft rejection?)
submitted by cassdawg(924)

TL;DR: T-cells are primarily responsible for both acute (weeks to months) and chronic (months to years) rejection; this would be acute rejection [FA2020 p119]

Hyperacute rejection (minutes): from pre-formed antibodies in the recipient which trigger an immune response in the recipient via complement activation (Type II hypersensitivity)

Acute Rejection (weeks to months): recipient T-cells recognize donor MHC on donor dendritic cells (Type IV hypersensitivity); humoral component (Type II hypersensitivity) to a lesser extent AFTER the T-cells have recognized the MHC as foreign

Chronic (months to years): recipitent T-cells recognize alloantigens [which are antigens which would be self in a normal tissue in the donor, but are recognized as foreign in the recipient] presented by recipient dendritic cells (Type IV hypersensitivity); humoral component (Type II hypersensitivity) AFTER the T-cells have recognize the MHC as foreign

... yotsubato made a comment on nbme19/block3/q#27 (74 yo man; continuous systolic-diastolic bruit over R posterior flank)
submitted by yotsubato(961)
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tWha saw ungiconsf rof me in isth qeusnoit asw taht eh ash an cetua ioerantspetn. atTh dditn eamk sesen to ..e.m He vdeil 47 sryae whti arlen reytra ionssste nad now sha nnpiheoesrty esacbeu fo it!?

... peteandplop made a comment on nbme19/block3/q#39 (45 yo man, lost outdoors in the Rocky Mountains for 10 days)
submitted by peteandplop(22)

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

... the_enigma28 made a comment on nbme19/block3/q#40 (25 yo woman requests prenatal diagnosis at 12 weeks gestation)
submitted by the_enigma28(30)

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 +
... cassdawg made a comment on nbme19/block3/q#46 (52 yo man, sudden onset of substernal chest pain)
submitted by cassdawg(924)

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/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(924)

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). +1
hiroshimi  Also, PCT and thick ascending tubule are the two areas that are most susceptible to hypoxic injury in the kidneys. +
... iceberglettuce made a comment on nbme19/block0/q#0 (A newborn delivered at term to a...)
submitted by iceberglettuce(8)

Complete Androgen Insensitivity Syndrome (CAIS):

  • Mutated androgen receptor (AR) in 46 XY (male fetus)
  • Y chromosome is present, so SRY gene will code for testis determining factor, and therefore Leydig and Sertoli cells are present.
  • Leydig cells are producing testosterone, but lack of functioning AR means no male external/internal structures. External genitalia "defaults" to female.
  • Sertoli cells produce Mullerian Inhibitory Hormone (MIH), which inhibits female internal structures. --> The absence of any internal genitalia means MIH is working, so choice D is wrong.
... icedcoffeeislyfe made a comment on nbme19/block0/q#0 (23-year-old woman...heparin...decreased platelet count)
submitted by icedcoffeeislyfe(35)


In heparin induced thrombocytopenia IgG Ab are developed against platelet factor 4 leading to thrombosis and thrombocytopenia

FA2020 pg 436

cbay0509  thank you +
... icedcoffeeislyfe made a comment on nbme19/block0/q#0 (During an experiment, a researcher blocks the...)
submitted by icedcoffeeislyfe(35)

FA2020 pg 48

retrograde transport= dynein

anterograde transport= kinesin

REaDY? AttacK!