An enzymatic approach to lipoprotein quantification.

Lipoprotein cholesterol levels were determined without ultracentrifugation by using modified enzymatic methods for cholesterol, high-density-lipoprotein (HDL) cholesterol, and triglyceride and the formula, low-density-lipoprotein (LDL) cholesterol = total cholesterol-HDL cholesterol-triglycerides/5. The methods for cholesterol and triglyceride determinations were standardized for accuracy and precision by the Center for Disease Control's Lipid Standardization Laboratory, which monitored this laboratory for 16 months. The lipoprotein cholesterol values obtained correlated well with lipoprotein cholesterol values determined at the Minnesota Lipid Research Clinic Laboratory using ultracentrifugation. LDL cholesterol determined at the Minneapolis Veterans Administration Hospital Laboratories (Y axis) produced a curve with an intercept of 9.38 mg/dl, a slope of .977, standard error of the estimate (Sy.x) of 8.8 mg/dl, and a correlation coefficient (r) of .983 (n = 32). HDL cholesterol was Y = 0.998 X + .89 mg/dl, Sy.x = 1.6 mg/dl (r = .984, n = 53), and very-low-density-lipoprotein (VLDL) cholesterol was Y = 1.010 X -1.32 mg/dl, Sy.x = 1.3 mg/dl (r = .996, n = 54).