Cálculo de la concentración de colesterol de la lipoproteína de baja densidad: análisis de regresión versus fórmula de Friedewald / Estimation of low density lipoprotein cholesterol: regression analysis versus Friedewalïs formula

ABSTRACT

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. Aim: To compare Friedewald formula and regression analysis for the calculation of LDL cholesterol. Material and methods: One hundred and fifty plasma samples from asymptomatic adults (aged 47.7 ñ 13 years, 50.6 percent 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 ñ 39.7 mg/dl, HDL cholesterol was 35.57 ñ 0.8 mg/dl and TG was 128.4 ñ 65.4 mg/dl. Mean values for LDL cholesterol were significantly higher than those estimated by the Friedewald formula (136.4 ñ 37.9 mg/dl and 114.1 ñ 37.4 mg/dl respectively, p<0.001) with a mean underestimation of 16.4 ñ 11.7 percent. 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