title: The impact of delayed blood centrifuging, choice of collection tube, and type of assay on 25-hydroxyvitamin D concentrations.
abstract: Studies have examined the associations between cancers and circulating 25-hydroxyvitamin D [25(OH)D], but little is known about the impact of different laboratory practices on 25(OH)D concentrations. We examined the potential impact of delayed blood centrifuging, choice of collection tube, and type of assay on 25(OH)D concentrations. Blood samples from 20 healthy volunteers underwent alternative laboratory procedures: four centrifuging times (2, 24, 72, and 96 h after blood draw); three types of collection tubes (red top serum tube, two different plasma anticoagulant tubes containing heparin or EDTA); and two types of assays (DiaSorin radioimmunoassay [RIA] and chemiluminescence immunoassay [CLIA/LIAISON((R))]). Log-transformed 25(OH)D concentrations were analyzed using the generalized estimating equations (GEE) linear regression models. We found no difference in 25(OH)D concentrations by centrifuging times or type of assay. There was some indication of a difference in 25(OH)D concentrations by tube type in CLIA/LIAISON((R))-assayed samples, with concentrations in heparinized plasma (geometric mean, 16.1 ng ml(-1)) higher than those in serum (geometric mean, 15.3 ng ml(-1)) (p = 0.01), but the difference was significant only after substantial centrifuging delays (96 h). Our study suggests no necessity for requiring immediate processing of blood samples after collection or for the choice of a tube type or assay.
authors.affiliation: Division of Cancer Epidemiology and Genetics, National Cancer Institute, National Institutes of Health, Department of Health and Human Services, 6120 Executive Boulevard, Mailstop 7238, Rockville, MD 20852, USA. yuchu@mail.nih.gov
authors.forename: Chu-Ling
authors.initials: CL
authors.lastname: Yu
authors.forename: Roni T
authors.initials: RT
authors.lastname: Falk
authors.forename: Michael G
authors.initials: MG
authors.lastname: Kimlin
authors.forename: Preetha
authors.initials: P
authors.lastname: Rajaraman
authors.forename: Alice J
authors.initials: AJ
authors.lastname: Sigurdson
authors.forename: Ronald L
authors.initials: RL
authors.lastname: Horst
authors.forename: Louis M
authors.initials: LM
authors.lastname: Cosentino
authors.forename: Martha S
authors.initials: MS
authors.lastname: Linet
authors.forename: D Michal
authors.initials: DM
authors.lastname: Freedman
mesh_terms: D000925:Anticoagulants / Q000008:administration & dosage; D001777:Blood Coagulation / Q000187:drug effects; D001800:Blood Specimen Collection / Q000295:instrumentation* / Q000379:methods*; D002498:Centrifugation; D019411:Clinical Laboratory Techniques / Q000592:standards*; D004492:Edetic Acid / Q000008:administration & dosage; D006493:Heparin / Q000008:administration & dosage; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008163:Luminescent Measurements / Q000379:methods; D011786:Quality Control; D011863:Radioimmunoassay / Q000379:methods; D015203:Reproducibility of Results; D013997:Time Factors; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D000925:Anticoagulants; D014807:Vitamin D; D006493:Heparin; D004492:Edetic Acid; C104450:25-hydroxyvitamin D