Tartrate-resistant acid phosphatase (TRAP) is a version of acid phosphatase produced by osteoclasts, the cells that dissolve small amounts of bone, during bone resorption. Osteocalcin is a protein formed by osteoblasts and can enter the bloodstream. The level of osteocalcin in the blood reflects the rate of bone formation, thus it is a useful indicator of the function of osteoblasts. This test may be affected by use of the drug warfarin (Coumadin).
