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Comments ...

 +0  (nbme24#18)

Artery of ductus deferens is a branch of infeior vesical artery. So why is B wrong?

happysingh  the question is asking about "adequate arterial supply"

 +1  (nbme24#49)

What guarantee do we have that the roommate is going to stop smoking in the apartment by "asking" him to do so..?


 +2  (nbme23#31)

Several names are used for nucleated RBCs—erythroblast, normoblast, and megaloblast—with one minor variation in word sense. The name normoblast always refers to normal, healthy cells that are the immediate precursors of normal, healthy, mature (anucleate) RBCs. The name megaloblast always refers to abnormally developed precursors. Often the name erythroblast is used synonymously with normoblast.

From all the things they could test us on... :)


 +0  (nbme23#39)

HCO3- is needed to make CSF. Acetazolamide inhibits carbonic anhydrase and decrease HCO3- absorption from renal tubules.

mario  could be pseudo tumor cereberi, ttt is also acetazolamide and is more common in female obese BMI 35KG/M
mario  opening pressure could be normal in pseudo tumor cereberi

 +0  (nbme21#39)

Where is this even from? My mind's going hay wire trying to understand this.

sahusema  Hardy Wineberg equilibrium square root 900 = 30 1/2 of all offspring will be carriers so 30*.5 = 15 simple as that
maxillarythirdmolar  this deserves a million upvotes.

 +0  (nbme21#41)
  • "Since symptoms can increase in severity during the night, it could become difficult to fall asleep or return to sleep after waking up"

  • "RLS is one of several disorders that can cause exhaustion and daytime sleepiness, which can strongly affect mood, concentration, job and school performance, and personal relationships. Many people with RLS report they are often unable to concentrate, have impaired memory, or fail to accomplish daily tasks"

  • "RLS occurs in both men and women, although women are more likely to have it than men."

  • "the symptoms typically become more frequent and last longer with age".

Source: https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Restless-Legs-Syndrome-Fact-Sheet

Everything in the stem points towards restless leg syndrome.

Plus I thought you need 5/9 of the SIG E CAPS to diagnose depression.

Someone please explain :)





Subcomments ...

submitted by lsmarshall(191),

Flexor digitorum profundus is responsible for flexion of DIP. Medial aspect of the muscle (which flexes the 4th and 5th digit) is supplied by the ulnar nerve (C8, T1). The lateral aspect (which flexes the 2nd and 3rd digit) is innervated by the median nerve specifically the anterior interosseous branch (C8, T1). So the question is describing a laceration damaging the nerve supply to the DIP flexor of the 2nd digit (index finger). This is saying the medial nerve is being damaged (C8 and T1; lower trunk roots).

Lumbricals (1st/2nd, median; 3rd/4th, ulnar) are a group of muscles that flex at the MCP joint, and extend PIP and DIP joints.

Could remember as 'flexor digitorum profundus is profoundly long' since tendons insert on DIPs. Compared to flexor digitorum superficialis whose tendon wraps around profundus' superficially but inserts on PIPs.

toupvote  This is dumb but I remember FDP is needed for picking while FDS is need for scratching the superficial layer of the skin +2  
whoissaad  @lsmarshall Flexor digitorum superficialis inserts at the middle phalanges to be more specific. +  


submitted by dbg(23),

Imo, this answer choice is wrong, there is no problem in the process of collagen "synthesis" per se. The issue is with excessive synthesis and disorganized deposition. Not an 'abnormal synthetic process' - as would be in EDS, MF, Menkes, etc.

whoissaad  Exactly my reasoning for not choosing collagen "synthesis" +1  


submitted by alexb(12),

I confused myelodysplastic syndrome with primary myelofibrosis because I thought 2-3 of those RBCs looked like teardrop cells. Just like when they show an image for bullous pemphigoid and there's some weird second rip through the dermal/subdermal layer making me think it's not BP even though I don't know what else it would be. fml

whoissaad  Made the same mistake +  
targetusmle  i thought exactly the same!! 2 cells looked like tear drop cells :/ +  


submitted by kentuckyfan(17),

Since the pain is radicular, a disc herniation is most likely.

charcot_bouchard  Why it cant be a lumbar vertebra fracture +  
whoissaad  @charcot The patient is young and doesn't have any risk factors for weak bones. Also, disc herniation is a common problem in the young. The disc gets fibrosed and stiff in the elderly so they have less chance for disc herniation. So basically age was the key to answering this question. +  


submitted by gh889(36),

Referring to NRTIs and NNRTIs as mainstay of treatment

Mainstay: efavirenz (NNRTI), tenofovir (NRTI), and emtricitabine (NRTI)

ususmle  I guess he is asking about integrate,,,,, where his should be integrated into host dna to get replicated .. triple therapy includes. 2drugs NRTIs and other one is integrate +  
whoissaad  @ususmle NRTIs would still inhibit DNA synthesis since they mess with the reverse transcriptase which is needed to make viral DNA. +1  


submitted by hayayah(399),

Femfibrozil is a fibrate, used for lowering TG levels.

mousie  I also chose Gemfibrozil too because its the best TG lowering drug listed but I can see where there might be some red flags for this drug in the way they asked the question... 40 year old obese woman with some upper abdominal pain ..... HELLO GALL STONES which is a common adverse outcome of Fibrates. +2  
uslme123  Well I didn't wanna give a fat, forty, female, that smokes a fibrate. So a statin, for me, was the best next option. +2  
whoissaad  Used same reasoning to choose statins. Fibrates are the main drug of choice for hypertriglyceridemia but given her symptoms, statins made more sense. Why do they do this to us... +  
roaaaj  what a tricky question! there are multiple factors should be taken in consideration.. she has triglyceridemia which put her in risk of pancreatitis, and most importantly atherosclerotic disease, and all of that would outweigh the risk of giving her gallstone. +  


submitted by d_holles(36),

This question confused me bc I thought loperamide could not cross the BBB and therefore could not cause respiratory depression (mu-opioid agonism at the brainstem results in CNS/respiratory depression, 1). But @dr.xx is correct in noting that ↓ RR and CNS depression in the Pt should call for an mu-opioid antagonist rather than bethanchol (cholinomimetic) to treat constipation.

  1. https://anesthesiology.pubs.asahq.org/article.aspx?articleid=2675905
nwinkelmann  http://medresearch.in/index.php/IJPR/article/view/782/1271 This explains a case in an infant. "Respiratory depression and coma after overdosage have been shown to be reversible by injection of naloxone [6]. Owing to its structural similarity to opioid, loperamide toxicity can be reversed by using Nalaxone which is a specific opioid antagonist acts competitively at opioid receptors. Naloxone hydrochloride is usually given intravenously for a rapid onset of action which occurs within 2 minutes." +  
yb_26  FA 2019: "Loperamide has poor CNS penetration" - so it still penetrates => can cause respiratory depression +1  
whoissaad  Also maybe because the blood brain barrier in a baby is not developed as well as in an adult. +  


submitted by yotsubato(264),

In biology, phase variation is a method for dealing with rapidly varying environments without requiring random mutation. It involves the variation of protein expression, frequently in an on-off fashion, within different parts of a bacterial population. As such the phenotype can switch at frequencies that are much higher (sometimes >1%) than classical mutation rates. Phase variation contributes to virulence by generating heterogeneity. Although it has been most commonly studied in the context of immune evasion, it is observed in many other areas as well and is employed by various types of bacteria, including Salmonella species.

https://www.wikiwand.com/en/Phase_variation

whoissaad  is it the same thing as antigenic variation? +3  
dorsomedial_nucleus  No, antigenic variation involves genomic rearrangement Phase variation can be thought of as MORE or LESS of something. An on/off switch. No DNA is being rearranged, just under or overexpressed in response to the environment. +  


submitted by nwinkelmann(93),

This article explains the pathophysiology well: https://www.ncbi.nlm.nih.gov/books/NBK431048/.

The right ventricle is primarily supplied by the RCA which also supplies the SA node and AV node (90% of hearts because they are right dominant), leading to loss of contractility of the right side, and thus fluid buildup causing elevated central venous pressure. Elevated pressures in the liver and portal system would lead to hepatomegaly and free fluid accumulation in the peritoneum.

henoch280  Hellppp. pls why is it not decreased capillary oncotic pressure? +  
whoissaad  @ henoch280 Because there is no change in the levels of protein in the blood. +  


submitted by hopsalong(3),

This question has a lot of answer options, and you arrive at Nephrolithiasis by throwing out all the other options by what is missing.

A, B - Cortical Necrosis and Papillary Necrosis almost always occur in the setting of ischemia. Previously healthy 28 year old man has no evidence of significantly decreased renal perfusion.

C - Acute Tubular Necrosis is what you should think of with Salicylate (NSAID) toxicity. There are many other nephrotoxic drugs that cause ATN, but think of ATN as drug induced kidney damage.

D - Cystitis - Flank pain is related to kidney injury, not bladder damage. Cystitis could be possible in ascending UTI, but the patient has no fever and is male (much less common in males).

E - Glomerulonephritis - This gets into nephrotic/nephritic syndromes. The stem mentions that he has blood in the urine which may lead you down the nephritic pathway, but he does not have any of the other associated symptoms.

F - Hypernephroma - Another word for Renal Cell Carcinoma. No weight loss or other cancer related symptoms (fatigue etc.)

G - Interstitial Nephritis - This is often a drug induced IMMUNE mediated nephrotoxicity. This is a type IV hypersensitivity reaction that occurs weeks to months after the start of medication (like NSAIDs). ATN is more associated with drug overdose while Interstitial is more associated with immune reaction. Intersitial Nephritis will have WBC casts in urine.

I - Pyelonephritis - Caused by ascending UTI but no fever is present.

This leaves Nephrolithiasis (H) as the correct answer. 85% of Nephrolithiasis is associated with hypoactive bowel sounds. The pain for nephrolithiasis can relapse and remit, and occasionally the pain can travel from the kidney (flank pain) to the scrotum as the stone moves through the ureter.

whoissaad  Great explanation. Always found it hard to differentiate between ATN and AIN due to NSAID use. This made it clear. Thanks! +1  
hyperfukus  yasss +  
dubywow  "occasionally writhes in pain" -- as a guy who has had a kidney stone, writhing in pain definitely hits the mark. Picture yourself knees on the ground, face on the couch, screaming incoherently while the paramedics are there because you can't control your own body movement and don't know if you're dying or whatnot from the canonball sized hole that (may or may not be) in your flank. Then imagine one of the paramedics is your premed study buddy. Never forget writhing and nephrolithiasis and premed study buddies. You will forever get this question correct in the future. +  


submitted by ergogenic22(42),

why is protection of the choroid plexus, from intraventricular rupture secondary to germinal matrix hemorrhage not a possible answer?

whoissaad  yes same question, both retinopathy and intraventricular hemmorage can occur due to high oxygen levels.. +  
cienfuegos  I mistakenly chose choroid plexus too, based on wiki seems this is most common cause of IVH in term infants: IVH in the preterm brain usually arises from the germinal matrix whereas IVH in the term infants originates from the choroid plexus. However, it is particularly common in premature infants or those of very low birth weight... Most intraventricular hemorrhages occur in the first 72 hours after birth. The risk is increased with use of extracorporeal membrane oxygenation in preterm infants. https://en.wikipedia.org/wiki/Intraventricular_hemorrhage#Babies +  
burak  choroid plexus is different than germinal amtrix +  


submitted by assoplasty(39),

I think the concept they’re testing is the increased TBG levels in pregnancy, and not just hyperthyroidism in general.

When screening for hypo/hyperthyroidism, TSH levels are ALWAYS preferentially checked because they are more sensitive to minute differences in T3/T4. Often times TSH levels can demonstrate a change even when T3/T4 levels are in the subclinical range. The only exception to this would be in pregnancy (and I guess maybe liver failure? I doubt they would ask this though). High estrogen levels prevents the liver from breaking down TBG, leading to increased TBG levels in the serum. This binds to free T4, decreasing the amount of available free T4. As a compensatory mechanism, TSH levels are transiently increased and the RATE of T4 production is increased to replenish baseline free T4 levels. However the TOTAL amount of T4 is increased.

The question is asking how to confirm hyperthyroidism in a pregnant woman --> you need to check FREE T4 levels (because they should be normal due to compensatory response). You cannot check TSH (usually elevated in pregnancy to compensate for increased TBG), and you cannot check total T4 levels (will be increased). You got the answer right either way but I think this is a different reasoning worth considering, because they can ask this concept in other contexts of hyper-estrogenism, and if they listed “TSH” as an answer choice that would be incorrect.

hungrybox  Extremely thorough answer holy shit thank u so much I hope you ACE Step 1 +3  
arkmoses  great answer assoplasty, I remember goljan talking about this in his endo lecture (dudes a flippin legend holy shit) but it kinda flew over my head! thanks for the break down! +2  
whoissaad  you mean total amount of T4 is "not changed"? 2nd para last sentence. +  
ratadecalle  @whoissaad, in a normal pregnancy total T4 is increased, but the free T4 will be normal and rest of T4 bound to TBG. If patient is hyperthyroid, total T4 would still be increased but the free T4 would now be increased as well. +  
maxillarythirdmolar  To take it a step further, Goljan mentions that there are a myriad of things circulating in the body, often in a 1:2 ratio of free:bound, so in states like this you could acutally see disruption of this ratio as the body maintains its level of free hormone but further increases its level of bound hormone. Goljan also mentions that you'd see the opposite effect in the presence of steroids and nephrotic syndromes. So you could see decreased total T4 but normal free T4 because the bound amounts go down. +  


submitted by nosancuck(37),

Yo dis B got NO INTERNAL FEMALE ORGANS

Why dat!???

We be lookin at someone with an SRY from dere Y chromie! Dey be a Y chromie Homie so they be makin some Testis Determinin Factor which I be sure makes some nice lil ANTI MULLERIAN FACTOR so dey aint got that Female Internal Tract u know what i be sayin

And since wimminz is da DEFAULT they stil be gettin dose pussy lips and breastes

meningitis  The above explanation is correct (disregarding the hard to read and unprofessional dialect) but just in case anyone was wondering: chromatin-negative= Just a quick way of knowing it was a boy. The term applies to the nuclei of cells in normal males as well as those in individuals with certain chromosomal abnormalities +11  
yotsubato  Turner syndrome patients are also chromatin negative as well though.... +3  
sympathetikey  I didn't know a complication post-meningitis was lack of humor. +2  
sympathetikey  Ah, didn't read the last line. Yeah, that is taking it a bit far +1  
niboonsh  yall are haters. this is the first explanation that has ever made sense to me +2  
arkmoses  https://www.youtube.com/watch?v=yuXL-3eoB-o&t=77s Interesting syndrome watching this helped me to put it into real life perspective, interesting points they have no pubic hair/body hair, they apparently also dont smell, and breast size is usually increased... +  
whoissaad  How does chormatin-negative indicate a normal cell? Isn't chormatin just condensed DNA? +1  
cienfuegos  According to this paper most individuals with Turner Syndrome are chromatin negative: "One of the initial laboratory procedures used to confirm or rule out this diagnosis involves a sex chromatin determination from a buccal smear. Cells from the lining of the mouth are stained for the presence or absence of X-chromatin or Barr bodies, which represent a portion of an inactivated X chromosome. The typical Turner’s syndrome patient, who has 45 chromosomes and only one sex chromosome (an X), has no Barr bodies and is, therefore, X-chromatin negative. This abnormal X-chromatin negative finding in the majority of Turner’s syndrome females is similar to the result found in a normal male, who also has only one X chromosome, and differs from the X-chromatin positive condition observed in the normal female, who has two X chromosomes. Occasionally, the patient with features of Turner’s syndrome is found to be X-chromatin positive." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6233891/ +  
hyperfukus  i really hate haters this is awesome! +  


submitted by vi_capsule(6),

HTN emergency, Sodium Nitroprusside. Unlike hydralazine a balanced vasodilator (vein = arteriol)

sympathetikey  Well then, I guess we should just forget about our old pals the Alpha-2 agonists. Good call. I didn't even see that this was hypertensive emergency. Dumb on my part. +  
zup  so yea clonidine would be used for hypertensive urgency, but this guy is over 180 (210) so they have to use something like hydralazine or nitroprusside both will increase cGMP +  
whoissaad  Drugs used to treat HTN emergency: Nitroprusside Labetolol Nicardipine Clevidpine Fenoldapam Clonidine +1  


submitted by yotsubato(264),

Why is this NOT chancroid? Theres nothing here that rules it out.

drachenx  Chancroid is described as an ulcer.. whilst in this question they mentioned "vesicles". Pretty much only herpes is vesicular +2  
whoissaad  They mentioned ulcers too. I chose chancroid as well, couldn't find a clue to rule it out. Also thought "discharge" was pointing you towards a bacterial infection. But guess I'm wrong :) +  
emmy2k21  I think NBME/USMLE writers make the assumption the patient is in America unless specified otherwise. Chancroid is not common in the US. If the question stem mentions a developing country, then chancroid can make your differential list. +1  


submitted by neonem(257),

Major risk factor for aortic dissection is hypertension, and in this case might be due to cocaine use, which causes marked hypertension. Dissections cause a tear in the tunica intima -- blood can flow backwards into the pericardium and cause tamponade. This manifests as crackles in the lung due to poor left ventricular function (filling/diastolic problem due to compression).

forerofore  there is another clue, the man has diminished pulses in just one arm, which means that the left subclavian artery must be involved somehow, and an aortic dissection would be the best answer explaining this. +3  
temmy  please why is there where a diastolic mumur? +1  
whoissaad  @temmy Aortic dissection especially near the root of aorta can lead to dilatation of the aortic valves, which can lead to Aortic regurgitation (diastoic murmur at left sternal border) +3  
garibay92  Does anyone know why is this patient's tepmerature elevated? +  
ratadecalle  @garibay92, not important for this question I think but cocaine can cause malignant hyperthermia +1