Comparison of intravenous (3-amino-1-hydroxypropylidene)-1, 1-bisphosphonate and volume repletion in tumour-induced hypercalcaemia.

In a group of thirty patients with tumour-induced hypercalcaemia the effects of volume repletion and intravenous (3-amino-1-hydroxypropylidene)-1, 1-bisphosphonate (APD) were examined. Volume repletion was only partially effective in lowering serum calcium and raising glomerular filtration rate and it increased the tendency towards hypomagnesaemia. In twenty-nine of the patients serum calcium, serum magnesium, and glomerular filtration rate were rapidly restored to normal by intravenous APD, in doses of 1.75-30 mg/day. Tubular reabsorption of phosphate was lower than normal in five of nine patients in whom it was studied and remained unchanged despite correction of hypovolaemia and serum and urine calcium levels or changes in parathyroid hormone. These findings suggested that tumours may produce a phosphate-lowering factor. The improvement in clinical condition with volume repletion depends on its ability to adjust calcium excretion to the abnormal production of calcium from bone. APD, in contrast, returns pathological bone destruction to normal without any undesirable side-effects.