Friedewald's Method underestimates LDL-Cholesterol even at Lower Range of Triglyceride.

Although Friedewald’s method is routinely used and convenient for clinical practice in measuring serum cholesterol level, it is not recommended for use in non-fasting blood samples or the presence of hypertriglyceridemia (>400 mg/dL) or type III hyperlipoproteinemia. To compare LDL-cholesterol (LDL-C) determined by direct homogeneous method with LDL-C determined by the Friedewald’s formula. It was a hospital based cross sectional study. A total of 1018, 10-12 hours fasting serum samples were taken. Triglyceride (TG) and total cholesterol (TC) were assessed by enzymatic colorimetric method; direct LDL-C and high density lipoprotein (HDL-C) by homogeneous enzymatic colorimetric assay in Cobas c 311 of Roche. LDL-C was calculated using Friedewald’s method.Pearson’s correlation and paired t-test. The mean LDL-C showed significant difference (p 400 mg/dL. There was significant correlation between direct and Friedewald’s calculated LDL-C (r=0.966). We also found -5%, 8.7%, -17.9%, -23.7% and -39% negative error in calculated LDL-C with direct LDL-C at TG ≤100, 101-200, 201300, 301-400 and >400 mg/dL respectively. Significantly higher percentage (38.2%) of subjects were classified having >130mg/dL LDL-C by direct homogenous method as compared with Friedewald’s method (24.9 %), with odds ratio of 1.87. Friedewald’s method for LDL-C estimation can’t be used for assessment of patients having hypertriglyceridemia.