A patient on long-term omeprazole therapy has a serum magnesium of 0.55 mmol/L (normal 0.7-1.0). Which statement BEST explains this finding?
- A PPIs reduce gastric acid needed for magnesium ionisation in the gut
- B PPI-induced hypomagnesaemia is due to impaired active magnesium transport in the small intestine ✓
- C Omeprazole directly inhibits renal tubular magnesium reabsorption
- D PPIs increase intestinal motility, reducing contact time for magnesium absorption
Correct answer: B. PPI-induced hypomagnesaemia is due to impaired active magnesium transport in the small intestine
Explanation
Long-term PPI use (typically >1 year) can cause hypomagnesaemia by impairing active magnesium transport through TRPM6/TRPM7 channels in the intestinal epithelium; the exact mechanism is not fully elucidated but appears to involve interference with transient receptor potential channels. Passive paracellular magnesium absorption, which is acid-independent, is less affected. Renal magnesium handling is normal. The condition resolves upon discontinuation of the PPI.
Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.