Hypercalcemia calls first for supportive measures, eg, adequate hydration, movement or mobilization of the patient to the greatest amount tolerated, and reevaluation of drugs being taken. When immediate lowering of the serum calcium level is not clinically mandatory, oral administration of furosemide, corticosteroid, or phosphorus should be considered. In acute emergencies, saline loading and parenteral furosemide therapy should be tried first, except in a patient with renal failure and congestive heart failure, in whom peritoneal dialysis or hemodialysis should be used instead. Calcitonin can be given for the first 12 to 24 hours to lower serum calcium concentration until a definitive management plan is formulated. Corticosteroid, if not contraindicated, should be started as soon as possible. In severe primary hyperparathyroidism with hypophosphatemia, phosphorus can be given intravenously until oral phosphate therapy can be established. Surgery, of course, should be performed as soon as possible. In most cases of neoplasia, mithramycin given according to a recommended schedule is safe and frequently effective. In desperate cases, additional use of prostaglandin synthesis inhibitors probably now is justified by empirical observations. All of these therapeutic measures are used only to stabilize electrolyte balance so that the primary cause of the hypercalcemia can be treated.