title: Effects of total cholesterol and triglyceride on the percentage difference between the low-density lipoprotein cholesterol concentration measured directly and calculated using the Friedewald formula.
abstract: BACKGROUND
  We elucidate how the triglyceride (TG) and total cholesterol (TC) concentrations affect the percentage difference (%DeltaLDL) between the low-density lipoprotein cholesterol (LDL-C) concentration evaluated by direct measurement (DLDL-C) and calculated using the Friedewald formula (FLDL-C), under conditions allowing the calculation.
  
  
  METHODS
  Serum concentrations of TC, TG, high-density lipoprotein cholesterol (HDL-C), and DLDL-C were measured and the FLDL-C and %DeltaLDL were calculated for 38,243 Koreans who had TG values <4.52 mmol/L. The DLDL-C was measured using the homogeneous Kyowa Medex assay (Kyowa, Tokyo, Japan). The %DeltaLDL was calculated using the equation: [(FLDL-C-DLDL-C)/DLDL-C]x100.
  
  
  RESULTS
  The mean %DeltaLDL-C was -9.1+/-6.4%. The %DeltaLDL differed by more than +/-5% in 75.4% of the subjects, and the FLDL-C was lower than the DLDL-C in 96.3%. The mean %DeltaLDL-C for the group with the highest TG and lowest TC was 11.8-fold that for the group with the lowest TG and highest TC.
  
  
  CONCLUSIONS
  Under conditions satisfying the requirements of the Friedewald formula, the DLDL-C and FLDL-C differed significantly over the concentration ranges of both TC and TG. In an evaluation of patients with hyperlipidemia, the Friedewald calculation may underestimate the risk for coronary heart disease.
authors.affiliation: Department of Laboratory Medicine, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea.
authors.forename: Kyung Ran
authors.initials: KR
authors.lastname: Jun
authors.forename: Hae-Il
authors.initials: HI
authors.lastname: Park
authors.forename: Sail
authors.initials: S
authors.lastname: Chun
authors.forename: Hyosoon
authors.initials: H
authors.lastname: Park
authors.forename: Won-Ki
authors.initials: WK
authors.lastname: Min
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D008076:Cholesterol, HDL / Q000097:blood*; D008078:Cholesterol, LDL / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014280:Triglycerides / Q000097:blood*
chemical_list: D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides