GI System MCAT Practice Question
A 52-year-old man with a 15-year history of alcohol use disorder presents with chronic abdominal pain, steatorrhea, and weight loss. Laboratory studies show elevated fecal fat (>7 g/day) and fat-soluble vitamin deficiencies. Imaging reveals pancreatic atrophy with fibrosis and fatty infiltration. Secretin stimulation testing demonstrates markedly diminished bicarbonate and enzyme output from the pancreatic ducts. Which of the following best explains the pathophysiology of this patient's malabsorption?
Answer choices
- ADecreased pancreatic lipase secretion impairs fat digestion, and reduced bicarbonate output prevents acid neutralization in the duodenum, allowing pepsin to remain active and digest pancreatic enzymes
- BLoss of acinar cells reduces pancreatic enzyme secretion, while decreased ductal cell bicarbonate output results in duodenal acidification that inactivates lipase and reduces micelle formationCorrect answer
- CPancreatic fibrosis physically obstructs the pancreatic duct, preventing enzyme delivery to the duodenum while compensatory increased gastric lipase production is insufficient to maintain fat digestion
- DReduced pancreatic juice volume decreases the osmotic load in the duodenum, which slows intestinal transit time and impairs nutrient absorption
- EDiminished bicarbonate secretion leads to excessive gastric acid reflux into the small intestine, causing mucosal atrophy and reduced absorptive surface area
- FLoss of pancreatic enzymes is compensated by increased small intestinal bacterial lipase, but the lack of bicarbonate causes bacterial overgrowth that consumes remaining nutrients
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