Caillot-Augusseau A, Vergely N, Soler C, Pernot J, Calatoru V, Bruleport V, Clavier A, Estour B
Laboratoire central de Médecine Nucléaire, CHRU de Saint-Etienné.
Ann Endocrinol (Paris). 1995;56(6):591-8.
Osteocalcin or bone GLA protein (BGP) can be used as well as a peripheral marker of the action of hormones on osteoblast. In the present study, we report our clinical and biological results in three different conditions: the kits used for determination, the time and the hour of withdrawal. We used 4 different radioimmunoassay kits: two kits (Elsa-os-nat (cis), Osca-test (Henning)) detect intact osteocalcin molecules only and the two others (Elsa-osteo(cis), Ostk-PR(cis)) detect intact osteocalcin molecules and osteocalcin fragments. Time between collection and assay is important: we observed a diminution of osteocalcin level which can be due to the degradation of intact molecules, of 25% to 49% (depending on the kit used). The clinical profile was studied with circadian rhythm. We observed a variation of osteocalcin level in 30% of circadian rhythm according to the hour of collection sample. In conclusion, we have seen two differents situations at risk of wrong interpretation due to low level BGP: inadequate serum collection or single blood collection instead of circadian cycle.
