title: Variations observed for insulin concentrations in an interlaboratory quality control program may be due to interferences between reagents and the matrix of the control materials.
abstract: The present study was carried out to observe the behaviour of insulin concentrations in an interlaboratory quality control program from BioRad Laboratories (Irving, CA) applied to Immulite 2000 (Diagnostics Product Corporation, Los Angeles, CA) for three control materials of Lyphocheck Immunoassay Plus Control. Insulin was measured for 261 consecutive working days in a year using a solid-phase immunometric chemiluminescent assay; likewise insulin was measured for 55 days during a period of 4 months in a pool of sera obtained from patients with insulin concentrations within the normal range of our laboratory. The results from each control material were classified in three groups according to the closeness among concentrations and time; mean concentrations were significantly different between consecutive groups for the three control materials (p<0.0001). However, no differences were observed in samples from pool sera. The variations observed in insulin concentrations of the control materials may be due to some interferences or matrix effect on the control material caused by the reagents to quantify insulin in the Immulite 2000.
authors.affiliation: Hormone and Genetic Section (Biochemistry Department), IDIBELL-Hospital Universitario de Bellvitge, Feixa Llarga s/n, 08097, L'Hospitalet de Llobregat, Barcelona, Spain.
authors.forename: Raúl Bonnin
authors.initials: RB
authors.lastname: Rigo
authors.forename: Mariona García
authors.initials: MG
authors.lastname: Panyella
authors.forename: Luis Roncero
authors.initials: LR
authors.lastname: Bartolomé
authors.forename: Pedro Alía
authors.initials: PA
authors.lastname: Ramos
authors.forename: Pilar Rosel
authors.initials: PR
authors.lastname: Soria
authors.forename: Miguel-Angel Moreno
authors.initials: MA
authors.lastname: Navarro
mesh_terms: D006801:Humans; D007118:Immunoassay / Q000379:methods; D007202:Indicators and Reagents / Q000737:chemistry*; D007328:Insulin / Q000032:analysis*; D011786:Quality Control; D015203:Reproducibility of Results
chemical_list: D007202:Indicators and Reagents; D007328:Insulin