Automated enzymatic standardized lipid analyses for plasma and lipoprotein fractions

Excellent normal ranges for plasma lipid and lipoprotein cholesterol levels have been developed by the Lipid Research Clinics program, standardized by the Centers for Disease Control (CDC). However these values were generated by methods not currently in use in most clinical chemistry laboratories. Automated enzymatic methods for cholesterol, triglycerides and free glycerol determinations, as well as a dextran sulfate-Mg2+ procedure for separation of high density lipoproteins (HDL) with standardization are described. Similar methods for the measurement of unesterified cholesterol and phospholipids are also given. Serum pools for total cholesterol with values ranging from 1220-3490 mg/l produced coefficients of variation (CV) less than or equal to 2.85%; reference values for low total cholesterol samples in a range of 280-727 mg/l gave CV of 4.35% or less; HDL cholesterol reference values of 265-640 mg/l yielded CV less than or equal to 3.70%; and values for triglycerides between 0.74 and 3.05 mmol/l gave CV of 4.22% or less through three to eight testing cycles (9-24 mth). These data indicate that long term CDC standardization of total cholesterol, triglycerides, and HDL cholesterol can be obtained with automated enzymatic methods utilizing commercially available reagents.