Hypercalcemia of malignancy: treatment with intravenous dichloromethylene diphosphonate.

Twelve patients with hypercalcemia associated with various malignancies were treated with intravenous dichloromethylene diphosphonate (Cl2MDP), a potent inhibitor of osteoclastic bone resorption, in doses of 2.5 mg/kg of body weight initially and 5.0 mg/kg thereafter for up to 7 days. Mean serum calcium concentration fell from 13.8 +/- 0.6 mg/dL (SEM) before Cl2MDP to 9.8 +/- 0.7 mg/dL (SEM) (p less than 0.001) after 7 days. Urine calcium excretion fell from 775 +/- 95 mg/g creatinine (SEM) to 272 +/- 70 mg/g creatinine (SEM) (p less than 0.005), and urine hydroxyproline excretion fell from 144 +/- 28 mg/g creatinine (SEM) to 78 +/- 18 mg/g creatinine (SEM) (p less than 0.05) after treatment with Cl2MDP. The Cl2MDP was well tolerated, and adverse effects were limited to asymptomatic hypocalcemia in two patients. The ability of Cl2MDP to correct hypercalcemia and reduce urine calcium and hydroxyproline excretion in these patients is consistent with the hypothesis that increased bone resorption is primarily responsible for this complication of malignancy and suggests that Cl2MDP may be highly useful in managing this condition.