A Simple Enzyme-Linked ImmunosorbentAssay of Human Osteocalcin

A heterologous ELISA for measurement of osteocalcin (bone Gla-protein) is described, involvingbiotinylatedbo-vine osteocalcin and polyclonalantibodies. The log-linear range was 2.3-37.5 g/L. Between-run (total) and within-run CVs (n = 10) were 5.7-6.4 and 5.9-6.1%, respec-tively; analytical recoveries ranged from 92 % to 108%. Comparison of our method (x) with an RIA (y) yielded y = 1.lOx- 0.01 g/L, S = 1.4 gIL, r = 0.958 (n = 167). Serum osteocalcin in healthy premenopausal women (n = 29) was 8.7 ± 3.3 gIL (mean ± SD) and 11.8 ± 4.5 gIL in early-postmenopausal women (n = 24). The as-say was evaluated in a double-blind placebo-controlled study of healthy early-postmenopausal women, treated for 12 months with either (a) estrogen valerate plus me-droxyprogesterone acetate (n = 18), (b) 17/3-estradio