Abnormal circulating hormone concentration Abnormal circulating osteocalcin level 2017-09-16T11:25:47Z A deviation from the normal concentration of osteocalcin in the blood circulation. Osteocalcin, also known as bone gamma-carboxyglutamic acid (Gla) protein (BGP), is the most abundant noncollagenous protein of bone matrix. It is released by osteoblasts during bone formation and binds with the mineralized bone matrix. Osteocalcin has an endocrine function, regulating glucose and lipid homeostasis.