Calcium carbonate toxicity: the updated milk-alkali syndrome; report of 3 cases and review of the literature.

OBJECTIVE

To describe 3 patients with calcium carbonate-induced hypercalcemia and gain insights into the cause and management of the milk-alkali syndrome.

METHODS

We report the clinical and laboratory data in 3 patients who presented with severe hypercalcemia (corrected serum calcium > or = 14 mg/dL) and review the pertinent literature on milk-alkali syndrome.

RESULTS

The 3 patients had acute renal insufficiency, relative metabolic alkalosis, and low parathyroid hormone (PTH), PTH-related peptide, and 1,25-dihydroxyvitamin D concentrations. No malignant lesion was found. Treatment included aggressive hydration and varied amounts of furosemide. The 2 patients with the higher serum calcium concentrations received pamidronate intravenously (60 and 30 mg, respectively), which caused severe hypocalcemia. Of the 3 patients, 2 were ingesting acceptable doses of elemental calcium (1 g and 2 g daily, respectively) in the form of calcium carbonate. In addition to our highlighted cases, we review the history, classification, pathophysiologic features, and treatment of milk-alkali syndrome and summarize the cases reported from early 1995 to November 2003.

CONCLUSION

Milk-alkali syndrome may be a common cause of unexplained hypercalcemia and can be precipitated by small amounts of orally ingested calcium carbonate in susceptible persons. Treatment with hydration, furosemide, and discontinuation of the calcium and vitamin D source is adequate. Pamidronate treatment is associated with considerable risk for hypocalcemia, even in cases of initially severe hypercalcemia.