Serum osteocalcin is increased in patients with hyperthyroidism and decreased in patients receiving glucocorticoids.

Osteocalcin (OC) is a vitamin K-dependent protein which is synthesized by osteoblasts and is present in the circulation. We measured serum OC concentrations in 10 patients receiving corticosteroids (CS) for chronic obstructive pulmonary disease and in 9 hyperthyroid (HT) patients. Mean values ( +/- SE) were as follows: There was a significant correlation between OC and alkaline phosphatase (r = 0.607; P = 0.006) when CS and HT groups were combined. Elevated serum OC concentrations in hyperthyroid patients may reflect increased osteoblastic activity, while decreased levels in corticosteroid-treated patients may reflect decreased osteoblastic activity.