Apoplexy__

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Oct 20, 2012
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Just did a question on COMBANK where the patient presented with all the typical signs of malabsorption syndrome due to cystic fibrosis, and had to pick out a potential complication of the disease. I picked vitamin B12 deficiency, but the answer was diabetes mellitus.

I absolutely understand how both could be complications, I just thought B12 deficiency was a better choice - impaired exocrine function decreasing ability to cleave off the R factor binding B12, so that B12 is stuck and can't be freed up to bind intrinsic factor. Especially since the question stem focused on exocrine pancreas impairment, I figured I'd go with the exocrine complication. Weird thing is, the explanation didn't even address B12 deficiency as a feasible answer.

Is the bank wrong, or am I?
 

NeuroLAX

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Apr 17, 2012
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I think they were going for the most common complication, which would be DM not B12 deficiency. CFRD is the most common non-pulmonary complication of CF.
 

notbobtrustme

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Think what happens to the pancreas in CF. **** can't get out because of the mucus plugging the ducts, so the enzymes build up in the pancreas and basically auto-digest it. That blows the islet cells, which leads to diabetes. B12 deficiency is possible as well, but DM presents much sooner than B12 deficiency.