Evaluate bone disease.

Increased levels of osteocalcin are found in bone diseases characterized by increased bone turnover. Osteocalcin has been found to be elevated in Paget disease of the bone, cancer accompanied by bone metastases, primary hyperparathyroidism and renal osteodystrophy. Osteocalcin levels may serve as useful index in evaluating the therapeutic management of the patient.

Osteocalcin, or bone Gla protein (BGP), is the major non- collagenous protein of bone matrix. It has a molecular weight of approximately 5.8 kilodaltons and consists of 49 amino acids, including three residues of gamma-carboxygluta- mic acid. Osteocalcin is synthesized in bone by osteoblasts. After production, it is partly incorporated into the bone matrix and partly delivered to the circulatory system. The precise physiological function of osteocalcin is still unclear. A large number of studies have shown that the circulating level of osteocalcin reflects the rate of bone formation. Determination of serum osteocalcin has proved to be valuable as an aid in identifying women at risk of developing osteoporosis, for monitoring bone metabolism during the perimenopause and postmenopause and during antiresorptive therapy.