Abstract
Hypercalcemia is rare in women of child-bearing age, and most cases are due to primary hyperparathyroidism. A 28-year-old woman, 14 weeks pregnant with dichorionic diamniotic twins, presented to hospital with vomiting, muscle cramps, and weakness. She had been taking calcium carbonate for gastric reflux and nausea from 5 weeks of gestation. Investigations revealed severe hypercalcemia, metabolic alkalosis, and renal injury. She was transferred to intensive care, receiving fluid resuscitation and subcutaneous calcitonin followed by dialysis. Investigations revealed suppressed PTH and PTH-related peptide, negative malignancy screening and low vitamin D level. Calcium and renal function quickly normalized and with cessation of calcium carbonate remained normal throughout the rest of pregnancy. Reports of calcium-alkali syndrome causing severe hypercalcemia are scarce, with most cases occurring later in gestation. This case represents a dramatic presentation requiring renal replacement therapy early in twin gestation.