The serum osteocalcin levels in adult and aged hypothyroid patients.

Osteocalcin (OC) or the bone protein containing gamma-carboxyglutamic acid (BGP or Gla-P), is a specific and sensitive marker of bone turnover. A radioimmunoassay (RIA) system for human osteocalcin was developed with the sensitivity of 0.5 ng/ml. The osteocalcin was measured in sera from 33 hormonally and/or clinically hypothyroid patients: 12 adult and 21 aged patients. For comparison, blood samples were collected from 14 hormonally hyperthyroid adult patients in whom the OC levels were 16.23 +/- 7.57 ng/ml (mean +/- SD) and from hormonally euthyroid adult patients (previously treated hyperthyroid patients) having OC 9.76 +/- 5.32 ng/ml. Abnormal low OC levels were noted in the hypothyroid adult patients group: 1.04 +/- 0.23 ng/ml by comparison to the hypothyroid aged patients 3.76 +/- 2.38 ng/ml (p less than 0.001). Moreover, great variability of the OC serum levels was observed in the aged group, four patients hormonally eu- or hypothyroid having high OC levels in the range: 13.29-55.45 ng/ml and other three patients although hormonally euthyroid but clinically hypothyroid had low OC levels 0.88-2.27 ng/ml. The abnormalities of the OC levels in hypothyroid adult and aged patients are discussed.