[Osteocalcin, a marker in diseases with elevated bone metabolism].

Osteocalcin is synthesized by osteoblasts and its concentration in serum is increased when bone metabolism is raised. Radioimmunoassay of serum from 88 healthy adults gave a mean osteocalcin value for the whole group of 4.11 +/- 1.43 ng/ml. The level rose with age. In seven patients with primary hyperparathyroidism the mean value was markedly raised to 19.37 +/- 9.2 ng/ml, in 23 with metastasizing carcinoma of the breast it was elevated to 6.57 +/- 2.98 ng/ml. Serial measurements in 14 female patients over seven months revealed different changes in osteocalcin and alkaline phosphatase in some of them. In patients with breast cancer and soft-tissue metastases or without metastases both osteocalcin and alkaline phosphatase levels were normal. Three of 17 patients with multiple myeloma had increased osteocalcin levels. These results indicate that it is clinically helpful to know osteocalcin levels in primary hyperparathyroidism. Determination of osteocalcin concentration, in addition to that of alkaline phosphatase, can be of value in the postmastectomy management of patients with breast cancer, especially in the early recognition of bone metastases. The diagnostic value of osteocalcin levels in multiple myeloma remains undecided.