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.
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.
Jun
Kyung Ran
KR
Department of Laboratory Medicine, Asan Medical Center and University of Ulsan College of Medicine, Seoul, Korea.
Park
Hae-Il
HI
Chun
Sail
S
Park
Hyosoon
H
Min
Won-Ki
WK
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*
D008076:Cholesterol, HDL; D008078:Cholesterol, LDL; D014280:Triglycerides