Can diarrhea, alcohol, diuretics, and PPIs lower magnesium status?

Magnesium depletion commonly has multiple, additive causes, making diarrhea, alcohol exposure, and medication review particularly relevant in an older adult with low magnesium or related potassium/calcium abnormalities.

Clinical evidence

• Diarrhea: Chronic, high-volume, malabsorptive, or steatorrheal diarrhea causes magnesium depletion through fecal loss and reduced uptake. High-output intestinal states (often >1.5–2 L/day when associated with dehydration) can deplete magnesium substantially.
• Alcohol: Chronic alcohol-use disorder is strongly associated with magnesium deficiency. A systematic review/meta-analysis found hypomagnesemia in 44.4% of affected individuals, with reductions in total serum, ionized, and skeletal-muscle magnesium.
• Diuretics: Thiazides have the clearest population-level association. In a cohort of 9,820 people, thiazide use was associated with lower serum magnesium and roughly threefold greater odds of hypomagnesemia, especially with >390 days’ exposure. Risk appeared lower with concomitant potassium-sparing therapy.
• PPIs: Long-term PPI use is associated with hypomagnesemia (meta-analysis of 16 observational studies: adjusted odds ratio 1.71), with a higher-dose signal. Serious symptomatic cases are rare but may require stopping the PPI despite replacement.

Mechanisms and practical implications

• Diarrhea impairs absorption through rapid transit while increasing stool magnesium loss.
• Alcohol can produce renal tubular dysfunction, with inappropriately persistent urinary magnesium loss during hypomagnesemia; abnormalities may improve after abstinence.
• Loop diuretics reduce magnesium reabsorption in the thick ascending limb; thiazides impair distal-tubule handling.
• PPI-associated cases generally show low urinary magnesium, favoring impaired intestinal absorption, potentially involving TRPM6/TRPM7-mediated transport.

Bottom line

• The claim is well supported: each exposure can lower magnesium status, often through distinct but potentially additive gastrointestinal and renal mechanisms. Assessment should include magnesium, kidney function, potassium, and calcium; urinary magnesium/fractional excretion can help distinguish renal wasting from gastrointestinal loss.