Plasma osteocalcin in man.

A radioimmunoassay for bovine osteocalcin has been developed. Human osteocalcin reacted identically with the bovine standard, allowing the use of this assay to measure human plasma osteocalcin. Levels were determined in 212 healthy subjects (124 men, 88 women) with an age range of 20 to 66 years. The distribution of these was skewed to the right, with the mean being 14.7 ng/ml (range 4 to 40) and the geometric mean 12.2 ng/ml. There was no alteration with age and no difference between males and females. High levels were found in chronic renal failure, Paget's disease of bone, and in primary hyperparathyroidism with severe bone disease, and there was a significant positive correlation of osteocalcin with plasma alkaline phosphatase. Low levels were found in pregnancy. Evidence is presented which suggests that the high levels measured probably reflect intact osteocalcin and not immunoreactive fragments. Our data are compared with those reported by others. Areas of disagreement are noted and discussed.