Improved in vitro stability of serum osteocalcin by using a new commercially available antiproteolytic compound

The effect of a commercially available antiproteolytic compound (OSCAstabil ) on the degradation in vitro of serum osteocalcin (Oc) was investigated in serum samples stored at 22, 4 or -30 degrees C (n = 20) or subjected to re peated freeze-thaw cycles (n = 8). The addition of the stabilizing agent im mediately after serum preparation increased the Oc stability from < 3 to 6 h at 22 degrees C, from < 3 h to 3 days at 4 degrees C and from 1 day to mo re than 3 days at - 30 degrees C. Up to three freeze-thaw cycles had no inf luence on the Oc stability, either with or without the stabilizer. The obvi ously prolonged Oc stability at 22 and 4 degrees C offers a more convenient and reliable Oc estimation procedure for clinical practice. The use of thi s antiproteolytic agent can be recommended in order to retard the in vitro degradation of serum Oc, not only for clinical routine, but also for studie s on metabolic bone diseases. (C) 1999 Elsevier Science B.V. All rights res erved.