title: [Study of variations of osteocalcin concentrations in function of collection, assay method and its nyctohemeral rhythm].
abstract: 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.
authors.affiliation: Laboratoire central de Médecine Nucléaire, CHRU de Saint-Etienné.
authors.forename: A
authors.initials: A
authors.lastname: Caillot-Augusseau
authors.forename: N
authors.initials: N
authors.lastname: Vergely
authors.forename: C
authors.initials: C
authors.lastname: Soler
authors.forename: J
authors.initials: J
authors.lastname: Pernot
authors.forename: V
authors.initials: V
authors.lastname: Calatoru
authors.forename: V
authors.initials: V
authors.lastname: Bruleport
authors.forename: A
authors.initials: A
authors.lastname: Clavier
authors.forename: B
authors.initials: B
authors.lastname: Estour
mesh_terms: D000328:Adult; D001800:Blood Specimen Collection / Q000379:methods*; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015675:Osteocalcin / Q000097:blood* / Q000502:physiology; D011863:Radioimmunoassay / Q000379:methods*; D011933:Reagent Kits, Diagnostic; D013997:Time Factors
chemical_list: D011933:Reagent Kits, Diagnostic; D015675:Osteocalcin
vernacular_title: Etude des variations de concentrations de l'ostéocalcine en fonction du mode de prélèvement, de la méthode de dosage et de son cycle nycthéméral.