A 4 month-old boy is brought by his mother due to large volume diarrhea and failure to thrive. The patient was born full term by normal vaginal delivery. On examination, the abdomen is distended with muscle wasting and mild lower edema. After a series of laboratory tests, a histochemical evaluation reveals absence of enteropeptidase activity in the proximal intestinal villi. Activity of which of the following substances is most likely impaired in this patient?

Question

Quizplus · Accepted Answer

Eductional Objective: The duodenal brush border enzyme enteropeptidase activates trypsin from its inactive precursor, trypsinogen.  Trypsin degrades complex polypeptides to dipeptides, tripeptides, and amino acids while activating other pancreatic enzymes.  Enteropeptidase deficiency impairs both protein and fat absorption, leading to diarrhea, failure to thrive, and hypoproteinemia.

A 4 Month-Old Boy Is Brought by His Mother Due