NBME 7 Question

[eddie13231]

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I am having trouble figuring out my wrong answer and have looked in FA, online, etc and have given up!

It was the one about the girl that had thrombocytopenia and amenia on admission and they did a plasma exchange and got better. It was autoimmune mediated correct? Anyway...I can't figure out what the correct answer is or I am missing something. They were asking what her RBC would look like on admission.

Can someone point my in the right direction?

 

[knuckles]

Haven't seen the question, but if she also had renal problems (ie uremia), sounds like it could be HUS. Did she eat a hamburger? If so, she would show schistocytes due to MAHA.

 

[eddie13231]

No hamburger involved in this one.

The more I think about it the more I think it was TTP but I am still thrown off by the anemia...I just hope this question doesn't show up on my exam!

 

[killinsound]

eddie is right i think.

 

[Vikingwizardguy]

Hey Buddy,

Although the anemia is confusing, if you identify what kind of anemia it becomes more straightforward (I actually felt that the TTP was more of a distraction since I don't know it that well). Anyhow, note how low the patient's haptoglobin is and how high the LDH is. Of the choices there, there's only one thing that could result in intravascular hemolysis (that I know of). Hope that helps 🙂

 

[PediatricsRocks]

For that one question about the kid who wasn't talking at age 20 months but his sister did talk at that age, what was the answer? Is it that boys talk later than girls usually?

Also, for those of you who took NBME 3:
Two drugs are synergistic with each other (individually each drug kills about the same number of bacteria, but given together, they kill even more). The answer, i.e the two synergistic drugs, I'm assuming, are tobramycin and ampicillin. Why wouldn't another answer choice listed, ceftazidime and erythromycin (low dose) be synergistic as well?

 

[eddie13231]

For that one question about the kid who wasn't talking at age 20 months but his sister did talk at that age, what was the answer? Is it that boys talk later than girls usually?

Also, for those of you who took NBME 3:
Two drugs are synergistic with each other (individually each drug kills about the same number of bacteria, but given together, they kill even more). The answer, i.e the two synergistic drugs, I'm assuming, are tobramycin and ampicillin. Why wouldn't another answer choice listed, ceftazidime and erythromycin (low dose) be synergistic as well?

The kid that wasn't talking-->need to do hearing assessment. This is always first line when trying to rule out autistic/aspbergers (sp?). Kids can not develop appropriate language skills because of congenital hearing loss.

NBME 3 question: don't know didn't take it 🙂 but i've seen questions before where aminoglycosides + penicillins are examples of classic combined treatments. like the bactieria is resistant to aminoglycoside but then penicillin is added and it works.

 

[eddie13231]

Hey Buddy,

Although the anemia is confusing, if you identify what kind of anemia it becomes more straightforward (I actually felt that the TTP was more of a distraction since I don't know it that well). Anyhow, note how low the patient's haptoglobin is and how high the LDH is. Of the choices there, there's only one thing that could result in intravascular hemolysis (that I know of). Hope that helps 🙂

Yeah that was just a hard question for me-I also remember the direct coombs test being negative which I thought ruled out a autoimmune hemolytic anemia. It looks like TTP has an anemia component due to intravascular desturction of RBC going through thrombi.

http://emedicine.medscape.com/article/779969-overview

It looks like coagulation factors would be normal (I thought that PT and PTT would be increased) because the coagulation cascade is not involved in the formation of thrombi. Its due to vWF in the circulation.

Just as long as I know its TTP and the answer was schistocytes then I am satisfied. Is this what you put and got it correct?

 

[username456789]

The kid that wasn't talking-->need to do hearing assessment. This is always first line when trying to rule out autistic/aspbergers (sp?). Kids can not develop appropriate language skills because of congenital hearing loss..

Yup. The "immediately" part might throw you off as being too drastic, but I agree with everything here.

 

[Vikingwizardguy]

Yeah that was just a hard question for me-I also remember the direct coombs test being negative which I thought ruled out a autoimmune hemolytic anemia. It looks like TTP has an anemia component due to intravascular desturction of RBC going through thrombi.

http://emedicine.medscape.com/article/779969-overview

It looks like coagulation factors would be normal (I thought that PT and PTT would be increased) because the coagulation cascade is not involved in the formation of thrombi. Its due to vWF in the circulation.

Just as long as I know its TTP and the answer was schistocytes then I am satisfied. Is this what you put and got it correct?

I can't verify for sure if it's right but here's what I got from the wiki page on TTP and it makes perfect sense:

"Red blood cells passing the microscopic clots are subjected to shear stress which damages their membranes, leading to intravascular hemolysis and schistocyte formation."

I think the negative coombs was to let you know that it wasn't ITP. The mechanism of hemolysis is not autoimmune based either. For some reason i always tend to think that TTP has a "DIC-like" feel to it so when you get a lot of these microscopic thrombin clots in your vessels, there's bound to be physical damage to erythros which leads to schistocyte formation. And with the other choices, I definitely used the "pick the word you've seen before" strategy. I'd never heard of some of the other choices. Also, the NBME tends to shy away from anything with eponyms and I think two or three of the other choices were eponyms.

 

[Ableton]

Just as long as I know its TTP and the answer was schistocytes then I am satisfied. Is this what you put and got it correct?

I just took the exam. I put schistocytes and got it correct... I figured the low platelets and high LDH point to TTP (since there is no autoimmune hemolysis).