Traditionally Friedewald formula has been used to calculate
low density lipoprotein cholesterol (
LDL-C) concentration though now direct homogenous methods for its measurement are also available. Clinical guidelines recommend the use of calculated
LDL-C to guide
therapy because the evidence base for
cholesterol management is derived almost exclusively from trials that use calculated
LDL, with direct measurement of
LDL-C being reserved for those patients who are non fasting or with significant
hypertriglyceridemia. In this study our aim was to compare calculated and direct
LDL and their variation at different
cholesterol and
triglyceride levels. Fasting
lipid profile estimation was done on 503 outpatients in a tertiary hospital. Both direct and calculated
LDL were then compared. Mean fasting direct
LDL was found to be higher than calculated
LDL in 87.1 % of subjects by 8.64 ± 8.35 mg/dl. This difference was seen a all levels of
cholesterol and
triglyceride. Using 130 mg/dl
LDL cholesterol as cut off fewer subjects were classified as high risk by calculated
LDL than direct
LDL. In conclusion, direct
LDL is higher than calculated
LDL. Compared with direct measurement, the Friedewald calculation underestimates the risk for
ischemic heart disease.