title: Immulite 2000 parathyroid hormone assay: stability of parathyroid hormone in EDTA blood kept at room temperature for 48 h.
abstract: Parathyroid hormone (PTH) concentrations were compared in serum and EDTA plasma from 36 patients attending a renal stone clinic. Serum PTH concentrations ranged from 0.9 to 10.9 pmol/L, with a mean of 4.6pmol/L. When serum and EDTA plasma results were compared, in samples frozen within 30 min of collection, EDTA plasma results were found to be significantly higher than those in serum (P < 0.0001; Wilcoxon test), with an average increase of 19.5% over the serum result. Results from EDTA-preserved blood left to stand at room temperature for 48 h were on average 14.8% lower than results from the corresponding EDTA plasma samples frozen within 30 min, with highly significant difference (P < 0.0001). Freshly frozen serum and 48h EDTA plasma PTH results were not significantly different. Parathyroid hormone in EDTA-preserved blood is not completely stable, and this could lead to misclassification of results for samples which are not frozen quickly.
authors.affiliation: Department of Chemical Pathology, Southampton General Hospital, UK.
authors.forename: H
authors.initials: H
authors.lastname: Omar
authors.forename: A
authors.initials: A
authors.lastname: Chamberlin
authors.forename: V
authors.initials: V
authors.lastname: Walker
authors.forename: P J
authors.initials: PJ
authors.lastname: Wood
mesh_terms: D001774:Blood Chemical Analysis / Q000379:methods*; D001800:Blood Specimen Collection / Q000379:methods*; D004492:Edetic Acid; D006801:Humans; D010281:Parathyroid Hormone / Q000097:blood* / Q000378:metabolism*; D013696:Temperature; D013997:Time Factors
chemical_list: D010281:Parathyroid Hormone; D004492:Edetic Acid