title: Effects of sample collection and handling on concentration of osteocalcin in equine serum.
abstract: A commercially available radioimmunoassay kit for measurement of human osteocalcin was validated for use in horses. For accurate measurement of equine serum osteocalcin, blood samples may be collected at a temperature between 20 and 25 C, then centrifuged within 90 minutes; serum may be stored at -20 C in plastic tubes for up to 26 weeks. Serum may be thawed and refrozen up to 5 times without significant change in measured equine serum osteocalcin concentration. Assay sensitivity was 0.16 ng/ml. Recovery of bovine osteocalcin standard added to equine serum was linear. Intra-assay coefficient of variation (x 100) for 2 equine serum pools was 6.9 (mean +/- SD, 13.9 +/- 1.0 ng/ml) and 7.5 (10.6 +/- 0.8 ng/ml) %. Interassay coefficient of variation for 3 equine serum pools measured in 12 assays was 12.5 (16.1 +/- 2.0 ng/ml), 12.7 (11.5 +/- 1.5 ng/ml), and 24.6 (3.0 +/- 0.7 ng/ml) %. Dilutional parallelism was documented by assaying pooled equine serum at 4 dilutions and correcting the mean result for dilution. Significant change was not observed in equine serum osteocalcin concentration for various time-of-day blood sample collections in horses housed under continuous lighting.
authors.affiliation: Department of Veterinary Diagnostic Medicine, College of Veterinary Medicine, University of Minnesota, St. Paul 55108.
authors.forename: E
authors.initials: E
authors.lastname: Hope
authors.forename: S D
authors.initials: SD
authors.lastname: Johnston
authors.forename: R L
authors.initials: RL
authors.lastname: Hegstad
authors.forename: R J
authors.initials: RJ
authors.lastname: Geor
authors.forename: M J
authors.initials: MJ
authors.lastname: Murphy
mesh_terms: D000818:Animals; D001800:Blood Specimen Collection / Q000379:methods / Q000662:veterinary*; D002940:Circadian Rhythm; D005615:Freezing; D006736:Horses / Q000097:blood*; D015675:Osteocalcin / Q000097:blood*; D011863:Radioimmunoassay / Q000379:methods; D011933:Reagent Kits, Diagnostic; D013696:Temperature
chemical_list: D011933:Reagent Kits, Diagnostic; D015675:Osteocalcin