[Induced hypocalcaemia test using salmon calcitonin as a means for the evaluation of osteoclastic activity (author's transl)].

The authors measured the degree of hypocalcaemia (delta Ca S), hypophosphataemia and the fall in urinary hydroxyproline excretion induced by an intramuscular injection of 100 MRC U of synthetic salmon calcitonin (S.C.T.) during the 24 hours following the injection. In 15 control subjects, the fall in plasma calcium was slight ( - 2.1 +/- 0.9 mg/l) but significant. In bone diseases involving hyperosteoclastosis, the degree of hypocalcaemia was much greater: 10.6 +/- 1.1 mg/l in 24 cases of Paget's disease, - 9.0 +/- 1.6 mg/l in 5 cases of diffuse malignant disease of bone, - 8.0 +/- 1.4 mg/l in 6 cases of primary hyperparathyroidism and - 3.5 +/- 0.8 mg/l in 13 cases of algodystrophy of the limbs. In the subjects studied as a whole there was a significant linear relationship between the delta Ca S and the extent of the trabecular surfaces of osteoclastic resorption, but not between delta Ca S and total 24 hour urinary hydroxyproline excretion. The S.C.T. hypocalcaemia test would appear to be a simple means for the evaluation of osteoclastic activity within the skeleton, and thus to select those bone disorders which should respond to antiosteoclastic therapy (calcitonin, diphosphonates).