Comparison of the renal and skeletal actions of calcitonin in the treatment of severe hypercalcaemia of malignancy.

The hypocalcaemic response to salmon calcitonin was separated into its renal and skeletal components during the treatment of 21 patients with severe hypercalcaemia complicating malignant disease. Inhibition of renal tubular calcium reabsorption by calcitonin may induce a rapid fall in serum calcium. The magnitude of this response depends in part upon the correction of volume depletion which is a common feature of hypercalcaemia from any cause. The adequacy of rehydration can be assessed from the relationship between serum calcium and the calcium excretion rate expressed in mumol/l glomerular filtrate (CaE). Not all patients show a good renal response to calcitonin and this may reflect secretions by the primary tumour of substances which inhibit the renal tubular actions of calcitonin. The response to rehydration may identify such patients and this has obvious practical implications for the choice of treatment.