title: Preanalytical stability of maternal serum markers hCGβ and PAPP-A.
abstract: Down syndrome maternal serum marker screening is based on a risk calculation including the free β - human chorionic gonadotropin (hCGβ) and pregnancy-associated placenta protein type A (PAPP-A). The aim of this study was to define the pre-analytical conditions of stability of these markers both in whole blood at 15-25 ̊C and, after centrifugation, in serum at 4-8 ̊C. 158 patients were included in the study. Two automated workstations were used for assays, Cobas 8000e602, Roche Diagnostics (58 patients tested) and DELFIAXpress, PerkinElmer (100 patients tested). The stability of markers was studied in whole blood (15-25 ̊C) 2, 4, 6 and 8 hours after sampling and in serum stored after centrifugation at 4-8 ̊C at 24, 72 and 120 hours. Variations were defined by (CT- C2)/C2, C2being the marker concentration at 2 hours and CTthe concentration at time T. In whole blood kept for 8 hours at 15-25 ̊C, hCGβ increased by a mean 2.4%, whereas the mean increase of PAPP-A was < 1%. In the serum kept for 5 days at 4-8̊C, the mean increase of hCGβ was 4.2%, with no change in PAPP-A. The impact of these variations on risk calculation is low. In conclusion, maternal serum can be store 8 hours at 15-25̊C in whole blood and 5 days at 4-8̊C after centrifugation and serum separation for Down syndrome maternal serum screening.
authors.affiliation: LBM Médilys, Lons-le-Saunier, France.
authors.forename: Béatrice
authors.initials: B
authors.lastname: Veyrat
authors.affiliation: LBM Oriade-Noviale, Meylan, France.
authors.forename: François
authors.initials: F
authors.lastname: Tosetti
authors.affiliation: Laboratoire de biostatistiques et d'informatique médicale, Faculté de médecine, Brest, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Morin
authors.affiliation: Service de biochimie et pharmacologie toxicologie, CHRU, Hôpital de la Cavale Blanche, Brest, France.
authors.forename: Marie-Pierre
authors.initials: MP
authors.lastname: Moineau
authors.affiliation: LBM Médilys, Lons-le-Saunier, France.
authors.forename: Andrée
authors.initials: A
authors.lastname: Piedimonte
authors.affiliation: Laboratoire Clément, Le Blanc-Mesnil, France.
authors.forename: Patrice
authors.initials: P
authors.lastname: Clément
authors.affiliation: Service de biochimie-hormonologie, Hôpital Robert Debré, AP-HP, Paris, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Dreux
authors.affiliation: Service de biochimie-hormonologie, Hôpital Robert Debré, AP-HP, Paris, France, Laboratoire de biochimie, Université Versailles Saint-Quentin, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Muller
mesh_terms: D015415:Biomarkers / Q000097:blood; D001793:Blood Preservation / Q000592:standards*; D001800:Blood Specimen Collection / Q000592:standards*; D018997:Chorionic Gonadotropin, beta Subunit, Human / Q000097:blood*; D004314:Down Syndrome / Q000175:diagnosis*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First / Q000097:blood; D011266:Pregnancy-Associated Plasma Protein-A / Q000032:analysis*; D011296:Prenatal Diagnosis / Q000592:standards*; D012034:Refrigeration; D015203:Reproducibility of Results
chemical_list: D015415:Biomarkers; D018997:Chorionic Gonadotropin, beta Subunit, Human; D011266:Pregnancy-Associated Plasma Protein-A
keywords: Down syndrome; free beta hCG; preanalytics; serum marker screening