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Osteocalcin in the blood
Last reviewed: 05.07.2025
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Osteocalcin is a vitamin K-dependent non-collagenous protein of bone tissue ( vitamin K is necessary for the synthesis of active protein centers that bind calcium ) - it is localized mainly in the extracellular matrix of bone and makes up 25% of the non-collagenous matrix. Osteocalcin is synthesized by mature osteoblasts and reflects bone tissue metabolism. High concentrations of parathyroid hormone in the blood have an inhibitory effect on the activity of osteoblasts that produce osteocalcin and lead to a decrease in its content in bone tissue and blood. 1,25(OH) 2D3stimulates the synthesis of osteocalcin in osteoblasts and increases its concentration in the blood.
Osteocalcin is a sensitive marker of bone tissue metabolism; changes in its concentration in the blood reflect the metabolic activity of bone tissue osteoblasts. More than 90% of osteocalcin synthesized by osteoblasts in young people and approximately 70% in mature people is included in the bone matrix, and the rest enters the bloodstream. Both intact osteocalcin (1-49 amino acids) and its large N-Mid fragment (1-43 amino acids) circulate in the blood. The concentration of intact osteocalcin in the blood is variable due to its destruction by proteases, so existing test systems mainly detect the N-Mid fragment.
Reference values (norm) of osteocalcin concentration in blood serum
Age |
Osteocalcin, ng/ml |
Children |
2.8-41 |
Women |
|
Before menopause |
0.4-8.2 |
After menopause |
1.5-11 |
Men |
3.0-13 |
Rickets in young children is accompanied by a decrease in the content of osteocalcin in the blood, and the degree of decrease depends on the severity of the rachitic process (most pronounced in stage II rickets). The content of osteocalcin in the blood of children with rickets is inversely related to the concentration of parathyroid hormone and in direct relationship with the concentrations of total and ionized calcium and calcitonin.
The concentration of osteocalcin in the blood increases in diseases characterized by increased bone metabolism ( Paget's disease, primary hyperparathyroidism, renal osteodystrophy, diffuse toxic goiter ).
When evaluating the results of osteocalcin research, it should be remembered that in cases of jaundice, lipidemia, and the intake of large doses of biotin, interference is possible and, as a consequence, elevated values of its concentration in the blood.
In patients with hypercorticism ( Itsenko-Cushing's disease and syndrome ) and patients receiving prednisolone, the osteocalcin content in the blood is significantly reduced, i.e. there is a close relationship between the severity of hypercorticism and the suppression of bone formation. The concentration of osteocalcin in the blood also decreases in patients with hypoparathyroidism.
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