Severe hypercalcemia without hypercalciuria in a previously healthy infant.

Williams-Beuren syndrome (WBS) is a multisystem disorder that has a broad range of clinical findings including characteristic facial appearance, supravalvular aortic stenosis, dental and developmental abnormalities, and endocrinologic disorders including but not limited to the development of hypercalcemia. We present the case of a 10-month-old girl, with a history of intrauterine growth restriction, who presented with symptoms of weight loss and poor feeding. She was found to have severe elevation of her serum calcium to 20 mg/dL. She was subsequently diagnosed with WBS by fluorescent in situ hybridization analysis. The exact etiology of hypercalcemia in patients with WBS is unknown, but there are several hypotheses. Treatment of hypercalcemia in WBS is achieved with intravenous (IV) fluids, loop diuretics, and a low calcium diet; bisphosphonate therapy is required if adequate decreases in the serum calcium level are not achieved with traditional therapy.