Endocrine Abstracts

Introduction: Hypercalcemia has a broad differential, including primary hyperparathyroidism, non-parathyroid hormone-mediated hypercalcemia, including humoral hypercalcemia of malignancy, or medication mediated. We report a case of severe hypercalcemia attributable to milk-alkali syndrome due to excessive calcium carbonate use.

Case: A 71 year-old female with a history of hypertension presented after a fall without loss of consciousness. She endorsed episodes of confusion for several days but denied any constitutional symptoms. Vitals were stable and physical exam was significant for dry mucous membranes. Labs were notable for calcium of 17.6 mg/dl, creatinine of 1.8 mg/dl (baseline 1 mg/dl), and bicarbonate of 33 mmol/l. The patient received fluids, calcitonin, and pamidronate, with normalization of her calcium level. She underwent a malignancy workup that revealed an appropriately suppressed parathyroid hormone (PTH) level, normal PTH-related peptide, serum and urine protein electrophoresis, and 1,25 hydroxyvitamin D. Malignancy workup with imaging of chest, abdomen and pelvis was unremarkable. Upon further investigation, the patient revealed that she had been taking 6 tablets of Tums, calcium citrate, and a glass of milk every day for two weeks. Her hypercalcemia was attributed to being medication-induced. The patient was discharged with recommendation to limit her calcium consumption with close outpatient follow-up.

Discussion: Milk alkali syndrome consists of a triad of hypercalcemia, alkalosis with varying degrees of renal dysfunction caused by the ingestion of large amounts of calcium and absorbable alkali. It is an often overlooked cause of hypercalcemia. Due to the availability of calcium carbonate over the counter (OTC), and lack of patient education on the ideal way of using the medication, the incidence of the milk-alkali syndrome is on the rise. It is crucial for physicians to inquire specifically about OTC drugs, medical foods, and supplements as they can lead to significant interactions and side effects.