Survey of total error of precipitation and homogeneous HDL-cholesterol methods and simultaneous evaluation of lyophilized saccharose-containing candidate reference materials for HDL-cholesterol
BACKGROUND: Standardization of HDL-cholesterol is needed for risk
assessment. We assessed for the first time the accuracy of HDL-cholesterol
testing in The Netherlands and evaluated 11 candidate reference materials
(CRMs). METHODS: The total error (TE) of HDL-cholesterol measurements was
assessed in native human sera by 25 Dutch clinical chemistry laboratories.
Concomitantly, the suitability of lyophilized, saccharose-containing CRMs
(n = 11) for HDL-cholesterol was evaluated. RESULTS: In the precipitation
method group, which included 25 laboratories and four methods, the mean
(minimum-maximum) TE was 11.5% (2.7-25.2%), signifying that 18 of 25
laboratories satisfied the TE goal of </=13% issued by the National
Cholesterol Education Program (NCEP). In the homogeneous HDL-cholesterol
method group, which included five laboratories, each performing two
different methods, the mean (minimum-maximum) TE was 9.5% (6.0-17.3%) for
the Boehringer assay and 15.7% (3.3-30.7%) for the Genzyme assay. For the
Boehringer homogeneous assay, one of five laboratories did not meet the TE
criterion, whereas for the Genzyme homogeneous assay, three of five
laboratories exceeded the 13% criterion. The biases on the HDL-cholesterol
values found by various precipitation methods were highly variable in all
CRMs, irrespective of the quality, whereas the biases found by the
homogeneous method from Boehringer were far less than +/-5% for the
highest-quality CRMs (CRMs 4-6). CONCLUSIONS: The NCEP goal was met by 24
of 35 laboratories assessed by use of native human sera. Selectively
pooled, lyophilized CRMs that are cryoprotected with 200 g/L saccharose
have ample potential for use in the standardization of homogeneous
HDL-cholesterol methods