Multicentric evaluation of the homogeneous LDL-cholesterol Plus assay: comparison with beta-quantification and Friedewald formula.
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.
Esteban-Salan
Margarita
M
Laboratorio de Bioquímica, Hospital de Galdakao, Barrio Labeaga s/n. Galdakao, 48960 Vizcaya, Spain. MARGARITA.ESTEBANSALAN@osakidetza.net
Aguilar-Doreste
José Angel
JA
Arranz-Pena
Maria Luisa
ML
Juve-Cuxart
Santiago
S
Gich-Salarich
Ignasi
I
Zapico-Muniz
Edgar
E
Ordonez-Llanos
Jordi
J
D015982:Bias; D001774:Blood Chemical Analysis / Q000379:methods*; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans; D007753:Laboratories
D008078:Cholesterol, LDL