Therapy of hypercalcemia of malignancy.

An appreciation of the pathogenesis of the hypercalcemia of malignancy is essential to its management. At the outset, since most patients with symptomatic hypercalcemia of malignancy are dehydrated, infusion of 2 to 3 liters of saline per day will at least partially reduce serum calcium levels. Induction of calciuresis by infusing larger volumes of saline simultaneously with parenteral administration of furosemide may reduce the serum calcium concentration to normal in the short term. Of major importance in long-term therapy, however, are drugs that inhibit bone resorption, a major cause of hypercalcemia. These include calcitonin, plicamycin, glucocorticoids, prostaglandin synthetase inhibitors, and the diphosphonates. These agents may provide long-term control of hypercalcemia in many patients. Reduction of intestinal calcium absorption by dietary means or by glucocorticoid therapy is often effective in the rare subset of patients with increased serum levels of 1,25-dihydroxyvitamin D. Oral and intravenous phosphorus therapy may be effective via unknown mechanisms in some patients. The diphosphonates, in particular, should greatly facilitate management of both acute and chronic hypercalcemia of malignancy. Daily intravenous infusion of etidronate disodium (etidronate) with saline over a period of three to six days, for example, appears to be a safe and effective means of restoring serum calcium concentrations to the normal range. Study results have shown that more than 90 percent of patients have a response to etidronate. Oral administration of the drug has been demonstrated to maintain normal serum calcium concentrations.