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 +0  (nbme20#31)

not sure if you all have seen the uworld chart Ddx for back pain but i found it really helpful. ill summarize it here: condition (key feature): degernative osteoarthritis (positional relieved with rest), radiculopathy - disc herniation(radiates to the leg aka lasegue sign), spinal stenossi(pain with standing), spondylorpathy(relieved with exercise, and ddominant at rest), spinal metastasis(constant pain, worse at night, not relieved by positional changes), vertebral osteomyelitis(focal tenderness, acute back pain, and fever), aortic dissection (severe restrosternal pain, radiating to the back)


 +0  (nbme20#19)

SPOLIER ALERT for future readers, the content following may contain subjects seen in other NBMEs


 +0  (nbme20#14)

"However, in the years, the bacterial pattern of splenectomy sepsis have been changing. The most important capsulated pathogen is Streptococcus pneumoniae (Str. Pneumoniae), but Haemophilus influenza (H.Influenzae) and Neisseria meningitidis (N. meningitidis) are also significant. In a study of 1991,36 reporting 349 episodes of sepsis in patients with asplenia, 57% of infections and 59% of deaths were caused by Str. pneumoniae." https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4621170/

honestly i tried to find data to support E.Coli or any higher risk of gram - sepsis, but pneumo is still numero uno


 +0  (nbme20#16)

Pt 1 (takes citric acid)

Pt 2 (takes candy)

Pt 1 (2x saliva = high flow rate, 2xNaCl [irrelevant - ignore])

Pt 2 (1x saliva = low flow rate, 1xNaCL [ignore not imp])

Pt1 = citric acid stim* ductal cell to secrete intracellular ductal storage of bicarb. bicarb neutralizes citric acid. thus low bicarb.

Pt2 = low flow rate, thus more bicarb reabsorbed out of duct. thus low bicarb

why do they have the same bicarb, because low flow rate.

*via Ach signal transduction to increase intracellular ductal calcium release --> HCO3 stored inside ductal cell


 +0  (nbme20#16)

theres an association made in 2017 with trigeminal neuralgia and MS - which is what i think this pt has. key thing to note is that while all motor and sensory fibers of CN 5 enter at the level fo the pons (however some also do enter at the level of medulla and even the sc via the spinal tract of 5 to synapse with the long sensory nucleus of 5) heres the link of trigeminal neuralgia and MS: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5649347/


 +0  (nbme20#49)

severe hypertension leads to hyperplastic arteriolosclerosis leading to arteriolonephrosclerosis (FA'18 --pg 297)


 +1  (nbme21#47)

theres so much iron in the blood that it has to go somewhere. it goes into the cells in the body (increased ferritin) and it binds to the carrier transport protein transferrin. because it binds to all the transferrin you have low free transferrin. but your body senses the low free transferrin and goes "ok all my transferrin are full of iron I guess im ok i dont need anymore iron" so it stops making transferrin. so low transferrin or total iron binding capacity (remember this is just a fancy way of saying it doesnt want transferrin).... now %transferrin sat is just math (i hate math) its like this: iron/TIBC, we already got high iron so numerator is high, and low denominator bc like i said TIBC is low so overall your %transferrin saturation is very high. this is the best indicator for hemochromatosis


 +1  (nbme21#13)

pt sx not responsive to dietary changes or stress reduction. stress (cortisol) decreases prostaglandins 327 (roles of cortisol). so were told that shes reduced her stress so logically her cortisol would be less, disinhibiting prostaglandin production. But her Sx still persist? thats why i ruled out misoprosol. also i remember from sketchy that ppis are irreversible tbh im not really sure if my logical flow is right, but like the guy in the other comments said, omeprazole always. just like ACEi and octreotide baby


 +1  (nbme21#16)

TLDR: last sentence summarizes it

The exact mechanism underlying AVB following ASD closure remains speculative. We can hypothesize that the possible mechanism of AVB is an inflammatory response and subsequent edema as a correlative result of mechanical rubbing of the occluder against the proximal conduction system. The margins of the secundum atrial septal defect include Bachmann’s bundle, the primary path for electrical conduction from the sinoatrial node to the atrioventricular node. The atrioventricular conduction bundle, which emerges from Bachmann’s bundle in the atrioventricular node area to conduct electrical impulses to the Purkinje fibers, is especially prone to damage.

Atrioventricular Block Subsequent to Intraoperative Device Closure Atrial Septal Defect with Transthoracic Minimal Invasion; A Rare and Serious Complication https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3532427/


 +0  (nbme21#12)

remember sigmoid colon has the smallest diameter (hence why Left sided CRC produces the apple core) meaning that it is prone to higher pressures in accordance to laplace' law (pressure inversely proportional to diameter) thus small diameter = high pressure = prone to diverticula formation

chandlerbas  one more thing. this question is not realistic. 5 years of constipation, with fever and chills...yet no hematochezia? ya ok there
chandlerbas  wait never mind, the inflammation scars the vasa recta so no bleeding. thanks for coming to my ted talk

 +0  (nbme21#38)

The researchers found that people who participated in mentally challenging activities most often, both early and late in life, had a slower rate of decline in memory compared to those who did not engage in such activities. Even when people had plaques and tangles and other signs of damage to their brains, mental stimulation seemed to help protect memory and thinking skills, accounting for about 14 percent of the difference in decline beyond what would be expected (Prashanthi Vemuri, PhD, Elizabeth C. Mormino, PhD: “Cognitive Stimulating Activities to Keep Dementia at Bay.” Neurology, Vol 81. 2013)

also the way i see it, AD pts have problems with hippocampus (i.e. short term memory power house) so keeping notes and lists or whatevvaa might help slow their cognitive decline as theyll be keeping the hippocampus more active


 +0  (nbme21#5)

bronchus obstruction traps oxygen in alveoli no nitrogen able to enter (atmospheric air entering body (78% nitrogen and 21% oxygen, nitrogen is so important nitrogen bc it is a poorly absorbed gas and thus is in charged of keeping alveoli inflated) oxygen in the alveoli is absorbed into the blood reducing the volume of the alveoli alveolar collapse absorption atelectasis





Subcomments ...

submitted by ergogenic22(46),

aging results in increased arterial stiffness (change in Extra Ccellular Mmatrix composition - decreased elastin, increased collagen deposition); ISH is responsible for 60-80% of HTN cases in patients > 60. Also, decreased compliance as a result of aging causes increased pulse pressure

rio19111  why not dev. of coronary atherosclerosis? +  
pakimd  @rio19111 i think the Q stem is asking in absence of any lesions of blood vessels; the number and severity of which increase with age. So with normal aging SBP should increase in isolation which may then result in the development of coronary atherosclerosis- if that makes sense +  
chandlerbas  aging causes decreased compliance in large arteries: (1) accumulation of collagen and calcium (2) degraded elastin and large arteries accumulation and it also may have something to do with lipofuschin +  


Itraconazole requires the acidic environment of the stomach to be absorbed. Omeprazole inhibits the H+/K+ pump of the stomach, thereby decreasing the acidity of the stomach. So when the patient takes Omeprazole and Itraconazole together, Itraconazole won't be absorbed into the body. That's why it has no effect.

It's recommended to take medications at least 2 hours prior to taking an antacid.

necrotizingfasciitis  Just adding support to the above explanation: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3671798/ +1  
pakimd  do all azoles or just itraconazole only requires an acidic environment to be absorbed? +1  
chandlerbas  just itraconazole and posaconazole +1  
lilyo  @chandlerbas, where did you find this information? I was looking over this on FA but they do not mention it and I would like a bit more information. Thanks! +  


submitted by hayayah(413),

Capitate and lunate are in the center of the palm. Capitate is not an option, so lunate is the answer.

Dislocation of lunate may cause acute carpal tunnel syndrome.

yotsubato  Lunate is the only carpal bone that is frequently dislocated. Scaphoid is frequently fractured. Hook of hamate is also frequently fractured. +2  
redvelvet  and also point tenderness in the anatomical snuffbox may indicate a scaphoid fracture. +1  
chandlerbas  yes lunate is the most common dislunated carpal bone ;) +1  


submitted by dickass(13),

Got this one wrong because of those 2 unaffected children. Here's the explanation from FA pg 59:

Mitochondrial inheritance - Transmitted only through the mother. All offspring of affected females may show signs of disease.

Variable expression in a population or even within a family due to heteroplasmy.

Heteroplasmy basically means that multiple mitochondria are transmitted to each offspring. Their ratio may change at each generation, and cause more severe or less severe disease, even within the same family.

Those unaffected dudes lucked out.

dickass  That'll teach me not to skim FA, you really gotta look up the words you don't know. +  
chandlerbas  heteroplasmy is a fancy way of saying variable expressivity just specific to mitochondrial diseases i do declare +  


submitted by strugglebus(69),

Nowhere have I been able to find why the hell this is a thing.

yotsubato  Its not in FA, Sketchy, or Pathoma, or U world. I knew it wasnt cancer because its bilateral. And Diabetes made no sense to me. So I just threw down Drug effect and walked away. +2  
breis  same^^^ +  
feliperamirez  The only possible explanation I think is that she was under a K sparing diuretic, such as spironolactone (which would lead to gynecomastia). +  
chandlerbas  you had me at its not in sketchy ;) +  


submitted by nuts4med(3),

Anyone have an idea why the decreased arterial O2 saturation is incorrect? Assuming she has pulm edema since she has LE edema, wouldn't a lower O2 sat be expected too?

haliburton  I believe there would be no decrease in O2 saturation because oxygenated blood (high pressure) is shunted into deoxygenated circuit. As long as the lungs can keep up, this should increase venous oxygenation on average. +1  
hungrybox  ty both of you for this, was wondering the same thing +  
coxsack  O2 sat won’t change b/c you’re not adding deoxygenated blood to the arterial side. You’re just taking arterial blood and putting it into venous blood. Same reason why L->R cardiac shunts don’t decrease O2 sat (while in contrast, a R->L shunt would). +2  
hungrybox  just realized: the high pressure of the arterial system keeps out low-pressure venous blood in an AV fistula (probably obvious to most ppl but it was a eureka moment for me lol) +1  
chandlerbas  ya you wont have decreased arterial O2 sat because oxygenation of blood is perfusion limited (FA19 --654) therefore oxygenation of the blood happens within the first .3seconds of entering the pulmonary capillary that you could even handle having more deoxygenated blood enter +  


submitted by nwinkelmann(99),

So I looked into this further too because I pretty much know nothing about the make up of semen. From the research I found, as as stated below by yo, fructose is the most important constituent of semen in terms or sperm function. Below is information I found to address the other answer choices.

Zinc deficiency (in serum), per FA, has been implicated in delayed wound healing, suppressed immunity, male hypogonadism, decreased adult hiar (axillary, facial, pubic), dysgeusia, anosmia, acromdermatitis enteropathica (defect in intestinal zinc absorption), and may predispose to alcoholic cirrhosis. FA didn't specify the levels in the semen, but per the below article, seminal zinc content was found to have nor correlation to sperm/semen activity/level/etc. I don't know if we're supposed to know that, but now I do, lol. https://www.ncbi.nlm.nih.gov/pubmed/3570537.

As hungrybox mentioned, selenlium is only mentioned once in FA as a treatment for tinea, so I looked into it further. Selenium is a content of semen, but levels vary so much that it serves no prognostic clincal relevance to infertility, per this article: https://www.ncbi.nlm.nih.gov/pubmed/3235210.

To rule out all of the answers (because I didn't really know anything about the quality fo semen), I found this "By t-statistics, there was no significant difference in the semen Na concentration among the different groups (7 groups total based on sperm count), indicating the insignificant role of Na in sperm motility.". https://www.ncbi.nlm.nih.gov/pubmed/721152.

Finally, I don't think the 5-alpha reductase enzyme is actually in semen, but I could be wrong. Either way, it wouldn't be abnormally elevated or low if the testosterone levels are normal.

bartolomoose  as per goljan, selenium is involved in glutathione peroxidase +  
chandlerbas  selenium has a role in glutathione peroxidase. excess selenium = garlic breath, hair loss, and nail changes, might see peripheral neuropathy. deficiency (pt on TPN) = dilated cardiomyopathy +  
chandlerbas  also zinc aids in sperm motility https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4773819/ thats why i chose zinc but whateverrr im over it +  


submitted by nwinkelmann(99),

So I looked into this further too because I pretty much know nothing about the make up of semen. From the research I found, as as stated below by yo, fructose is the most important constituent of semen in terms or sperm function. Below is information I found to address the other answer choices.

Zinc deficiency (in serum), per FA, has been implicated in delayed wound healing, suppressed immunity, male hypogonadism, decreased adult hiar (axillary, facial, pubic), dysgeusia, anosmia, acromdermatitis enteropathica (defect in intestinal zinc absorption), and may predispose to alcoholic cirrhosis. FA didn't specify the levels in the semen, but per the below article, seminal zinc content was found to have nor correlation to sperm/semen activity/level/etc. I don't know if we're supposed to know that, but now I do, lol. https://www.ncbi.nlm.nih.gov/pubmed/3570537.

As hungrybox mentioned, selenlium is only mentioned once in FA as a treatment for tinea, so I looked into it further. Selenium is a content of semen, but levels vary so much that it serves no prognostic clincal relevance to infertility, per this article: https://www.ncbi.nlm.nih.gov/pubmed/3235210.

To rule out all of the answers (because I didn't really know anything about the quality fo semen), I found this "By t-statistics, there was no significant difference in the semen Na concentration among the different groups (7 groups total based on sperm count), indicating the insignificant role of Na in sperm motility.". https://www.ncbi.nlm.nih.gov/pubmed/721152.

Finally, I don't think the 5-alpha reductase enzyme is actually in semen, but I could be wrong. Either way, it wouldn't be abnormally elevated or low if the testosterone levels are normal.

bartolomoose  as per goljan, selenium is involved in glutathione peroxidase +  
chandlerbas  selenium has a role in glutathione peroxidase. excess selenium = garlic breath, hair loss, and nail changes, might see peripheral neuropathy. deficiency (pt on TPN) = dilated cardiomyopathy +  
chandlerbas  also zinc aids in sperm motility https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4773819/ thats why i chose zinc but whateverrr im over it +  


submitted by yo(26),

they're talking about a splenorenal shunt procedure

https://my.clevelandclinic.org/health/treatments/4950-distal-splenorenal-shunt

hungrybox  be honest did u know that before looking it up +2  
meningitis  @hungry, because you didn't know it, doesn't mean he didn't. This is a forum for answering questions and helping out, not dissing or showing off. Grow up before becoming a doctor. +1  
sympathetikey  Relax @meningitis. Hungry's just messin :) +1  
sbryant6  Looks like somebody needs an enema to get that stick out. +  
chandlerbas  ya'll are too TP/(TP+FN) lol +  


submitted by sympathetikey(312),

Inferior oblique = helps you look up & in.

Also, they said floor of the orbit, so it makes sense that the inferior muscles would damaged.

sahusema  I know you're right. I was just so uncomfortable picking an answer with "inferior rectus" because damage to the inferior rectus does nothing to explain the clinical findings of impaired upward gaze. Unless the muscle is physically stuck and can't relax or something +3  
emmy2k21  Agreed. Why would a dysfunctional inferior rectus contribute to impaired upward gaze??? I eliminated that answer choice and got it wrong :( +1  
dr_jan_itor  in the last sentence it asks you to assume an "entrapment", so it is actually the inferior rectus which is the cause of the upward gaze palsy. The entrapped muscle is functionally trapped in it's shortened position, thereby not allowing the orbit to gaze upward. +5  
chandlerbas  bam! dr_jan_itor just cleaned up that confusion +  


remember sigmoid colon has the smallest diameter (hence why Left sided CRC produces the apple core) meaning that it is prone to higher pressures in accordance to laplace' law (pressure inversely proportional to diameter) thus small diameter = high pressure = prone to diverticula formation

chandlerbas  one more thing. this question is not realistic. 5 years of constipation, with fever and chills...yet no hematochezia? ya ok there +  
chandlerbas  wait never mind, the inflammation scars the vasa recta so no bleeding. thanks for coming to my ted talk +1  


remember sigmoid colon has the smallest diameter (hence why Left sided CRC produces the apple core) meaning that it is prone to higher pressures in accordance to laplace' law (pressure inversely proportional to diameter) thus small diameter = high pressure = prone to diverticula formation

chandlerbas  one more thing. this question is not realistic. 5 years of constipation, with fever and chills...yet no hematochezia? ya ok there +  
chandlerbas  wait never mind, the inflammation scars the vasa recta so no bleeding. thanks for coming to my ted talk +1  


Irrerugularly Irregular rhythm = Afib Afib --> stasis of blood in the Heart ---> Thrombus formation Thrombus will embolize to the (likely) the popliteal artery leading to acute limb ischemia

194orbust  why would an embolectomy be favored over clopidogrel? +2  
194orbust  oh nvm......it's bc clopidogrel won't bust a clot, just prevents them from forming. +8  
chandlerbas  also the way i see it is the hommie has so much pain as indicated by "sudden onset of severe pain" so you want something fast and effective. surgery time! grab my scalpel! drugs could be indicated but arent an option even then heparin takes 20 to 60 minutes to work so +  


submitted by neonem(262),

This is a postpartum mood disturbance, a pretty common disorder that has to have an onset within 4 weeks of delivery to be termed as such. Postpartum blues is the most mild, with a 50-85% incidence rate (per FA 2018), usually resolves within 10 days and treatment is only supportive but need to follow-up to assess for possible postpartum depression. Postpartum depression = 10-15% rate, characterized by depressed affect, anxiety, poor concentration for greater than 2 weeks and needs to be treated w/ CBT + SSRI. I think the question is getting at screening for this and a potentially more problematic complication, postpartum psychosis.

thisisfine   Found this difficult because FA characterizes "thoughts of harming baby or self" as postpartum psychosis - which is super rare, and doesn't fit this case. Also, CBT is first line treatment for postpartum depression - so I still like the offer to refer to a therapist as the best choice. +1  
d_holles  Same @thisisfine. +1  
chandlerbas  i see what youre saying but we should make sure that the mother is alive for us to refer to a therapist. remember if shes willing to harm herself most likely also willing to harm the the little cutie baby....so asking for suicidal thoughts screens for progression to post partum psychosis with the aim to prevent the sentinel event: harm to the baby +  


submitted by assoplasty(41),

Fats are ketogenic (except odd chain FA), so they produce ketones for energy production (Acetyl-CoA) rather than glucose. If the question asked what the primary source of energy production was, it would still be glycogen (and not ketones), because this is within 24 hours. However after 24 hours the answer could be ketone bodies. Regardless, the question specifically said the pt had a serum glucose of 100, indicating that we are looking for something that provides a substrate for gluconeogenesis.

During periods of starvation, substrates for gluconeogenesis come from two sources: (1) breakdown of existing muscle, or (2) via odd-chain FA through propionyl-CoA. (*Valine also feeds into propionyl CoA, but is not involved during starvation --> see below)

(1) The alanine-pyruvate cycle provides this (glutamine in muscle + pyruvate --> alanine --> goes to liver --> transamination to alpha-ketoglutorate --> pyruvate is separated from glutamine --> glutamine goes to urea cycle, pyruvate goes on to gluconeogenesis). Lactate can also be used (this could have been a right answer if it were listed).

(2) Odd chain FAs are also glucogenic, but stearic acid (provided in the answer choice) isn’t odd chain, so it is only ketogenic and can be ruled out.

Although valine (and other branched a.a.) feed into Propionyl-CoA, they are not used in starvation because starvation strictly relies on hepatic gluconeogenesis. These a.a. are not metabolized in the liver because the liver lacks branched-chain a.a. transferase enzyme. In First Aid, Biochem section, under Fasting/Starvation, in both the “fasting state” (which is within the time frame of this question), or the “starvation state,” both utilize hepatic gluconeogenesis. My assumption is that valine is used during regular metabolism, and not during periods of starvation.

hello  I want to re-emphasize something that @assoplasty has already stated :). The Q-stem states serum glucose = 100, and the Q asks why the patient is able to maintain normoglycemia. Therefore, you can immediately eliminate choices A and C because acetoacetate and beta-hydroxybutyrate are sources of energy during ketogenesis -- ketogenesis does not provide glucose energy sources. +  
chandlerbas  ^ this checks out: valine and isoleucine are broken down in the muscle into branched chain 2 oxo acid via branched chain aminotransferase (reversible) then the valine and isoleucine leave the muscle and swims to the liver to be acted on by branched chain 2 oxo acid DH (irreversible). So bascially the process from taking BCAA valine and isoleucine requires 2 enzymes. the first enzyme is in the muscle, and the second enzyme is in the liver (for simplification purposes --> both organs contain both enzymes but dont have the same affinity for their substrate). source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1147506/?page=4 so you're right to say that the liver +  


submitted by jambo2222(13),

It’s an osteosarcoma. Sarcoma = hematogenous mets. It’s in the legs so think how a DVT goes to lung. Same idea.

tinydoc  Perfect way to remember it. Thank you! +  
chandlerbas  Iused the mnemonic PB (lead) KeTtLe....looking at the stem it said "osteolytic mass" meaning that it has to be either Breast, Kidney, thyroid or lungs. none of the rest are options leaving lungs. but jambo2222 very noiice that works too! +  


don't forget about the Mg block! . . . . . .



submitted by tinydoc(55),

Neuropathic Pain after stroke is central Post stroke pain Syndrome

caused by contralateral thalamic lesions

Pg. 504 FA19

chandlerbas  agreed! more specifically damage to the VPL +