osteocalcin
noun
os·teo·cal·cin
| \ -ˈkal-sən
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Medical Definition of osteocalcin
: a protein that is found in the extracellular matrix of bone and in the serum of circulating blood, is produced by osteoblasts especially in the presence of vitamin K but is not a collagen, and when present at excessive levels in serum may be indicative of various disorders (as Paget's disease or postmenopausal osteoporosis) of bone metabolism