Clinical Chemistry, Vol 40, 389-394, Copyright © 1994 by American Association for Clinical Chemistry

Nonlinearity of high-density lipoprotein cholesterol determinations is matrix dependent

MH Kroll and R Chesler
Clinical Pathology Department, Clinical Center, National Institutes of Health, Bethesda, MD 20892.

The majority of methods for determining high-density lipoprotein (HDL) cholesterol failed the 1991 College of American Pathologists (CAP) linearity survey (sets LN2-A, B, C). We hypothesized that they failed because of the survey material matrix. We evaluated linearity with dextran sulfate or phosphotungstate as the precipitating reagents for several methods: Ektachem; TDx; Sigma; Dimension; Cobas Fara, with Roche reagents; and the Hitachi 736, with precipitating reagents from Boehringer Mannheim Diagnostics. We tested CAP survey material, Sigma HDL-cholesterol control material, and a fresh serum pool for linearity, using the polynomial method. All of the methods were nonlinear for the CAP material and for the controls precipitated after dilution. Five of eight methods were linear for the control materials precipitated before dilution. All methods but one were linear for the serum pool. These results demonstrate that the source of the nonlinearity is located in the precipitation step and depends on the sample matrix.

The following articles in journals at HighWire Press have cited this article:

				N Gould, J Moller, and L Andrieux The commutability of external quality assurance serum and reference serum materials between the VITROS(R) Albumin Slide and four other routine albumin methods Ann Clin Biochem, January 1, 2008; 45(1): 76 - 82. [Abstract] [Full Text] [PDF]

				M. H. Kroll and R. Chesler The Nonlinearity Seen for LDL-Cholesterol with Lyophilized Material Is a Matrix Effect Clin. Chem., August 1, 1998; 44(8): 1770 - 1771. [Full Text] [PDF]