Serum osteocalcin in the management of myeloma

We have measured serum osteocalcin, a vitamin K-dependent glycoprotein synthesised by osteoblasts in 62 patients, 49 with myeloma, 26 at presentation and 23 previously treated, 7 with Waldenstrom's macroglobulinaemia (WM), and 6 with monoclonal gammopathy of uncertain significance (MGUS). Osteocalcin levels were normal in WM and MGUS. High values were found in 5/26 (19%) patients with myeloma at presentation. There was no relationship between serum osteocalcin and stage of disease. Osteocalcin was normal in all patients in plateau phase, falling to low levels in relapsed patients who failed to respond to further treatment. Serum osteocalcin may be a useful indicator of bone metabolism in myeloma.