[Differential diagnosis of hypercalcaemia by measurement of renal calcium excretion during parathormone administration (author's transl)].

Rapid differential diagnosis of hypercalcaemia due to primary hyperparathyroidism or malignancy with or without bone metastases may be life saving. A parathormone infusion test (6 USP units/kg body wt X 20 min) enables a differential diagnosis within three hours by means of measurement of renal calcium excretion. In normal persons calcium excretion decreased from 147 +/- 90 to 79 +/- 54 mumol/h (x +/- s, n = 10). In primary hyperparathyroidism with hypercalcaemia the high calcium excretion remained unchanged: 716 +/- 162 mumol/h before and 804 +/- 130 mumul/h 120 minutes after the PTH infusion (n = 12). In patients with hypercalcaemia caused by bronchial carcinoma with (n = 5) and without (n = 1) bone metastases calcium excretion decreased from 552 +/- 182 to 163 +/- 114 mumol/h. As a consequence of these data this test is advisable when the indication for operation in cases with hypercalcaemia has to be reached within a few hours.