An electrocardiogram revealed sinus tachycardia with a rate of 105/min. The results of portable chest radiography were unremarkable. Magnetic resonance imaging of the brain with and without gadolinium did not reveal acute hemorrhage, stroke, or progression of demyelinating disease since her last magnetic resonance image in February 2010. Her serum calcium level was markedly elevated at 14.6 mg/dL (15.2 mg/dL when corrected for an albumin level of 3.2 g/dL [to convert to grams per liter, multiply by 10]; reference range, 8.7-10.1 g/dL), and her ionized calcium level was 6.40 mg/dL (reference range, 4.64-5.20 mg/dL) (to convert both total and ionized calcium to millimoles per liter, multiply by 0.25). Her magnesium (1.3 mEq/L; reference range, 1.8-2.3 mEq/L; to convert to millimoles per liter, multiply by 0.5) and phosphorus (1.4 mg/dL; reference range, 2.4-4.6 mg/dL; to convert to millimoles per liter, multiply by 0.323) levels were low, whereas her serum urea nitrogen (48 mg/dL; reference range, 8-23 mg/dL; to convert to millimoles per liter, multiply by 0.357) and creatinine (1.32 mg/dL; reference range, 0.42-1.06 mg/dL; to convert to micromoles per liter, multiply by 88.4) levels were elevated. The patient's serum parathyroid hormone (PTH) level was 4 pg/mL (reference range, 12-65 pg/mL; to convert to nanograms per liter, multiply by 1), and her 25-OH D level was 103 ng/mL (sufficiency >30 ng/mL, excess >150 ng/mL). Her thyrotropin, free thyroxine, cortisol, serum protein electrophoresis, urine protein electrophoresis, angiotensin-converting enzyme, and PTH-related protein levels were normal.