Comparison of calculated low-density lipoprotein-cholesterol by Friedwald’s equation and direct low-density lipoprotein-cholesterol by homogenous assay

ABSTRACT

Background: LDL cholesterol is a known atherogenic factor and basis for risk classification of coronary heart disease. Reference method for measurement is beta-quantitation which is laborious and time consuming. The other method for measurement is direct homogenous assay which is costly so most laboratories use Friedwald’s formula for LDL measurement. Aim and Objectives: The aim of the study was to compare between calculated LDL by Friedwald’s formula and direct LDL by homogenous assay in fasting lipid profile samples. Material and Methods: We have taken data of 208 fasting lipid profile from past records after obtaining Institutional Ethics Committee permission. Patients with TG > 400 mg/dl were excluded from the study. Results: In our study, Pearson’s coefficient is 0.97 when TG < 200 mg/dl and Pearson’s coefficient is 0.95 when TG > 200 mg/dl. There is a less difference in patient’s risk classification by calculated LDL and direct LDL when TG < 200 mg/dl. Conclusion: Friedwald’s formula is a cost-effective method for measurement of LDL in comparison to homogenous assays. We can use calculated LDL when TG < 200 mg/dl without any risk of patient’s misclassification.