title: Multicentric evaluation of the homogeneous LDL-cholesterol Plus assay: comparison with beta-quantification and Friedewald formula.
abstract: OBJECTIVE
  To evaluate the analytical and clinical performance of a new version of the LDL-C Plus assay and compare it with the beta-quantification (BQ) method in a multicenter study.
  
  
  METHODS
  Direct LDL-C was measured in 169 fresh pooled samples and in 830 clinical samples with known LDL-C by BQ. The reactivity of lipoproteins and the effect of hemoglobin, bilirubin and chylomicrons (CM) were studied.
  
  
  RESULTS
  Direct LDL-C total imprecision was <2.2%; inaccuracy <+/-2.5% (unaffected by triglycerides up to 9.5 mmol/L); and total error 9.8%. Direct assay reacted with 95%, 50% and 25% of the cholesterol in the LDL, intermediate (IDL) and VLDL fractions, respectively. A significant association was observed with BQ. Icteric samples showed a negative bias and the effect of CM was variable. A positive bias was observed when VLDL-cholesterol/triglyceride ratio was >0.57.
  
  
  CONCLUSIONS
  LDL-C Plus assay represents a valid alternative to BQ for clinical laboratories.
authors: Laboratorio de Bioquímica, Hospital de Galdakao, Barrio Labeaga s/n. Galdakao, 48960 Vizcaya, Spain. MARGARITA.ESTEBANSALAN@osakidetza.net
authors: Margarita
authors: M
authors: Esteban-Salan
authors: José Angel
authors: JA
authors: Aguilar-Doreste
authors: Maria Luisa
authors: ML
authors: Arranz-Pena
authors: Santiago
authors: S
authors: Juve-Cuxart
authors: Ignasi
authors: I
authors: Gich-Salarich
authors: Edgar
authors: E
authors: Zapico-Muniz
authors: Jordi
authors: J
authors: Ordonez-Llanos
mesh_terms: D015982:Bias; D001774:Blood Chemical Analysis / Q000379:methods*; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans; D007753:Laboratories
chemical_list: D008078:Cholesterol, LDL