Too much of a good thing: OTC calcium carbonate overdose causing milk-alkali syndrome in a psychiatric patient.

BACKGROUND: In the United States, milk-alkali syndrome or calcium-alkali syndrome is the third most common cause of hypercalcemia, after primary hyperparathyroidism and malignancy. Clinically, patients present with a triad of hypercalcemia, acute kidney injury, and metabolic alkalosis. Classically, it has been associated with excessive intake of calcium and absorbable alkali, and recently it has become more common in postmenopausal females who ingest calcium supplements for osteoporosis. CASE PRESENTATION: Here, we present the case of a 72-year-old Caucasian female with a longstanding diagnosis of bipolar I disorder who presented to the Emergency Department (ED) with a sudden onset of generalized weakness, multiple falls, and altered mental status over the course of several days. On admission, she had elevated serum calcium, acute kidney injury, and metabolic alkalosis. CONCLUSIONS: This case underscores the importance of thorough medical and psychiatric assessment in patients presenting with altered mental status, particularly in those with a history of overdosing. It also highlights the need for close collaboration between psychiatry and internal medicine in the management of metabolic disturbances that may mimic or exacerbate psychiatric symptoms. A stepwise approach to the diagnosis and treatment of hypercalcemia is reviewed, with particular attention to considerations unique to psychiatric populations.