[Treatment of hypercalcemia of myelomatous origin with intravenous diphosphonates]

Diphosphonates were administered intravenously to 4 patients with myeloma-induced hypercalcaemia. All patients received EHDP 4.3 mg/kg/day for 3 to 8 days. One of them, whose hypercalcaemia recurred, was later treated with Cl 2 MDP 5 mg/kg i.v. for 8 days. In 2 patients EHDP infusions were followed by EHDP administered orally (5 mg/kg/d) for 3 weeks, after which transiliac bone biopsy was performed. In all patients calcemia fell from 130 +/- 14 to 99 +/- 4 mg/l at the end of the intravenous treatment, with parallel decrease in calciuria. Histomorphometric analysis of the bone biopsies showed few osteoclasts but massive infiltration with plasmocytes. In one case, EHDP probably induced a deficit in mineralization. Intravenous diphosphonates therefore proved to be rapidly effective in the treatment of hypercalcaemia due to malignancy. However prolonged administration of EHDP in high doses is not recommended, as it may result in osteomalacia.