Antacid therapy--changes in mineral metabolism.

Antacid ingestion may lead to side-effects related to their chemical composition. Aluminum hydroxide may cause the phosphate depletion syndrome even during short-term administration of high doses in patients at high risk, such as alcoholics. Long-term intake may lead to bone demineralization and to osteomalacia. Fluoride complexing in the gut and prevention of fluoride absorption may be an additional factor. The clinical relevance of aluminum absorption in patients with normal renal function is not clear. In contrast, in patients with renal failure, aluminum hydroxide ingestion may contribute to an increasing hyperaluminemia. Hyperaluminemia and tissue deposition of aluminum in these patients may contribute to the dialysis-associated encephalopathy. Magnesium hydroxide causes an alkalinization of the urine due to magnesium absorption and urinary excretion. Thus, in renal insufficiency, a life-threatening hypermagnesemia may develop if magnesium-aluminum-containing antacids are prescribed. The milk-alkali syndrome, rarely observed nowadays, may be caused by calcium carbonate- and sodium bicarbonate-containing antacids. Hypercalciuria and alkaluria predispose to nephrolithiasis. The possibility that these disturbances in mineral metabolism will develop in patients with normal renal function is unlikely unless there is an abuse of these "over the counter" antacids.