A 55-year-old patient with GERD on long-term proton pump inhibitor therapy develops hypomagnesemia and recurrent Clostridioides difficile infections. PPI-induced hypomagnesemia occurs because PPIs:

• A Increase urinary magnesium excretion by inhibiting renal H+/K+ ATPase in tubular cells
• B Reduce gastric acid, impairing ionization of dietary magnesium salts needed for absorption
• C Inhibit magnesium absorption by blocking TRPM6/TRPM7 channels in intestinal epithelium ✓
• D Activate CYP3A4, increasing magnesium catabolism in the liver

Explanation

Long-term PPI use impairs active transcellular magnesium absorption in the small intestine by reducing the expression and activity of the TRPM6 and TRPM7 magnesium channels, which are the principal transporters for active intestinal magnesium absorption. Passive paracellular magnesium absorption (which is less affected by PPIs) cannot compensate. This explains why hypomagnesemia from PPIs is refractory to oral magnesium supplementation and resolves upon discontinuing the PPI. C. difficile risk increases because gastric acid normally kills ingested C. difficile spores.

Reference: KD Tripathi, Essentials of Medical Pharmacology, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.