Changes in plasma osteocalcin concentration following treatment with stanozolol.

Treatment of healthy, adult, human volunteers with stanozolol, 5 mg twice daily, for six weeks caused a marked elevation in circulating levels of osteocalcin. Plasma osteocalcin concentrations did not fall to pretreatment values for a period in excess of four weeks after the cessation of treatment but remained similar to levels whilst on treatment. At the same time, as the rise in plasma osteocalcin was seen, plasma alkaline phosphatase activity fell; however, in this case, a return to pretreatment levels occurred within four weeks of treatment ending. These data demonstrate that stanozolol has a detectable effect on the plasma concentration of a protein thought to be a marker of osteoblast activity, and that this effect continues for a period after treatment has been discontinued.