[Physiologic variations in plasma osteocalcin in the child and the adolescent]

Osteocalcin, the most abundant of non-collagen proteins in bone, is produced by osteoblasts and incorporated into the bone matrix. A small amount is circulated in the bloodstream where it can be detected by radioimmunologic assay. Serum assays in 128 children and adolescents showed that serum osteocalcin levels accurately reflect the various stages of statural growth: peak levels were found at three different ages, i.e. infants (21.8 +/- 4.9 ng/ml), children over seven (19.4 +/- 5.2 ng/ml), and adolescents undergoing the early stages of puberty (22.5 +/- 4.2 ng/ml). Although significant differences were found between each age group and the preceding or following group, these results can be applied to individual patients only for longitudinal studies.