A 48-year-old man with recurrent jejunal ulceration has fasting serum gastrin of 1200 pg/mL. He has steatorrhoea, yet faecal fat studies show his pancreatic lipase output after secretin stimulation is normal. The most likely explanation for his steatorrhoea is:
- A Autoimmune destruction of I cells reducing CCK release
- B Competitive inhibition of micelle formation by excess gastrin itself
- C Acid inactivation of pancreatic lipase and precipitation of bile salts in the duodenum due to pH below 4 ✓
- D Secondary lymphangiectasia obstructing lacteal drainage of chylomicrons
Correct answer: C. Acid inactivation of pancreatic lipase and precipitation of bile salts in the duodenum due to pH below 4
Explanation
In Zollinger-Ellison syndrome the massive acid load lowers duodenal pH below the optimum for lipase and precipitates glycine-conjugated bile salts, destroying mixed micelles even though enzyme secretion is normal. The pancreas works fine; the environment inactivates its products. This is why high-dose PPI therapy corrects the steatorrhoea.
Reference: Ganong's Review of Medical Physiology, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.