Woman with hypomagnesemia and hypocalcemia.

A 71-year-old woman was referred to the endocrinology clinic after several years of unresolved hypomagnesemia that required numerous hospital admissions to receive intravenous magnesium. She previously presented with palpitations on 3 occasions, and once with diarrhea and vomiting. The blood tests on all 4 presentations demonstrated severe hypomagnesemia (Table 1). Her medical history included type 2 diabetes mellitus and hiatal hernia. Her regular medications included simvastatin, esomeprazole, verapamil, pioglitazone, gliclazide, metformin, and calcium, magnesium, and vitamin D supplementation. Clinical examination in the endocrinology clinic was unremarkable, and no abnormality was demonstrated on electrocardiogram. An echocardiogram was normal. Laboratory results at this visit included serum magnesium 0.52 mg/dL (0.21 mmol/L) [reference interval 1.7–2.4 mg/dL (0.7–1.0 mmol/L)] and serum calcium 6.84 mg/dL (1.71 mmol/L) [reference interval 8.8–10.6 mg/dL (2.20–2.65 mmol/L)]. Serum albumin was 35 g/L (reference interval 35–52 g/L). The results of her other biochemical tests were unremarkable. Twentyfour-hour urine magnesium excretion was undetectable [reference interval 0.5–1.2 mg/dL (0.2–5.0 mmol/24 h)], as was random urine magnesium [ 0.25 mg/dL ( 0.1 mmol/L)]. Intact parathyroid hormone (PTH) was 20 ng/L (reference interval 15– 88 ng/L), inappropriately low in the presence of hypocalcemia. All analytes were measured with a Beckman Olympus AU2700 general chemistry analyzer with the exception of intact PTH, which was measured with a Beckman Coulter Access II. The patient gave full written consent for the use of her clinical information and laboratory tests for the purposes of a case report in the medical literature. DISCUSSION