[Should blood samples be drawn on heparin-anticoagulant for lipid analysis?]

Lipid profile is often performed on heparinized-plasma because nothing in particular is explained in the technical data sheet about anticoagulant and because few data (mainly with EDTA anticoagulant) are available in literature. In order to evaluate heparinized-plasma vs serum differences, 50 normo- or hyperlipidemic samples were collected and assayed in 3 clinical laboratories in Lyon on Hitachi analysers with Roche Diagnostic reagents. Lipid values are lower in plasma than in serum; the average negative bias for cholesterol levels is 2 to 4,5% and for triglycerides about 3%, depending on the laboratory; the effect on HDL-cholesterol values is not significant. These results were confirmed by manual procedure on 28 samples with Roche Diagnostic reagent and two similar other reagents (Biomerieux and Randox). A negative bias of 4% on total cholesterol and triglycerides levels is not very important for clinical diagnosis but it is more serious for LDL-cholesterol estimated with Friedewald equation; LDL-cholesterol value needs accuracy because it is a therapeutic goal with statin therapy and an high negative bias (until 0,70 g/L in our results) is unacceptable; moreover, there is a real risk of providing false total cholesterol results. Therefore it is essential to collect blood for lipid profile without any anticoagulant.