[Estimation of low density lipoprotein cholesterol concentration: regression analysis versus Friedewald's formula].
BACKGROUND
The Friedewald formula is used to estimate cholesterol of low density lipoprotein (LDL) from total cholesterol (CT), cholesterol of high density lipoprotein (HDL) and triglycerides (TG), but there are doubts about its precision.


OBJECTIVE
To compare Friedewald formula and regression analysis for the calculation of LDL cholesterol.


METHODS
One hundred and fifty plasma samples from asymptomatic adults (aged 47.7 +/- 13 years, 50.6% male) were analyzed. CT, HDL, LDL and TG were determined by enzymatic methods. Friedewald formula (LDLc = CT-HDL-(TG/5)) and multiple regression analysis were applied to estimate LDL concentration.


RESULTS
Mean total cholesterol was 175.3 +/- 39.7 mg/dl, HDL cholesterol was 35.57 +/- 0.8 mg/dl and TG was 128.4 +/- 65.4 mg/dl. Mean values for LDL cholesterol were significantly higher than those estimated by the Friedewald formula (136.4 +/- 37.9 mg/dl and 114.1 +/- 37.4 mg/dl respectively, p < 0.001) with a mean underestimation of 16.4 +/- 11.7%. LDL cholesterol values were directly proportional to TG concentration. Multiple regression analysis (LDLr = -14.376 + (age x 0.198) + (CT x 0.949) + (HDL x -0.474) + (TG x -0.064) showed no statistical differences with those obtained by the enzymatic method.


CONCLUSIONS
These results confirm the underestimation of LDL concentration by the Friedewald formula despite normal range of TG concentration. A multiple regression analysis should be used to estimate LDL concentration with precision.
Eblen-Zajjur
A
A
Departamento de Ciencias Fisiológicas, Facultad de Ciencias de la Salud, Universidad de Carabobo, Valencia, Venezuela. aeblen@uc.edu.ve
Eblen-Zajjur
M
M
D000328:Adult; D000368:Aged; D000465:Algorithms; D008078:Cholesterol, LDL / Q000097:blood*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D012044:Regression Analysis; D015203:Reproducibility of Results
D008078:Cholesterol, LDL