A patient on omeprazole develops peripheral neuropathy. What is the most likely cause?

• A. New diagnosis of DM
• B. Omeprazole
• C. Pernicious anemia
• D. Gastric cancer

Answer: (B)

Long-term suppression of stomach acid with a proton pump inhibitor like omeprazole can lead to vitamin B12 deficiency. The acid in the stomach helps release B12 from dietary protein so it can be absorbed with intrinsic factor in the ileum. When acid is reduced, B12 absorption falls, and deficiency can cause neurologic symptoms such as peripheral neuropathy from demyelination of neural pathways.

So, the neuropathy in this patient is most likely due to B12 deficiency from impaired B12 absorption caused by omeprazole. Other options don’t fit the mechanism as well: new diabetes could cause neuropathy but isn’t directly tied to the medication; pernicious anemia also causes B12 deficiency but the immediate link here is acid suppression; gastric cancer wouldn’t typically present with peripheral neuropathy.