Osteocalcin (OC) is a 49 amino acid peptide found exclusively in bone tissue and is highly conserved among species. It is a vitamin K- and D-dependent protein produced by osteoblasts, osteocytes and odontoblasts. It is deposited in extracellular bone matrix and is found in the serum. Serum osteocalcin, hydrolysed in the kidney and liver, is considered a specific marker of osteoblast activity and bone formation rate. It may be involved in regulation of osteoblast function, regulation of bone turnover and/or mineralization.