Validation of the Friedewald Equation for Evaluation of Plasma LDL-Cholesterol

Abstract

Summary In most clinical laboratories, low density lipoprotein (LDL) cholesterol is usually estimated indirectly with the Friedewald equation or directly with the N-geneous assay. We assessed LDL-cholesterol values obtained by both methods to find an appropriate fasting period and to assess the influence of the energy content of the last meal. Blood samples were taken from 28 healthy volunteers who had consumed a standard meal (107 g of carbohydrate, 658 kcal) followed by a fasting period of 12 and 18 h, or a high-energy meal (190 g of carbohydrate, 1011 kcal) with a fasting period of 12 h. Prolongation of the fasting period from 12 h to 18 h decreased glucose level, but did not decrease triacylglycerol, total cholesterol, or high density lipoprotein (HDL) cholesterol. LDL-cholesterol levels measured with the Ngeneous assay did not change (94.0 ± 21.5 to 96.3 ± 19.1 mg/dl). LDL-cholesterol levels calculated with the Friedewald equation were also similar after fasting periods of 12 h (98.5 ± 21.4 mg/dl) and 18 h (99.7 ± 20.2 mg/dl). The high-energy meal did not change the level of LDL-cholesterol measured with the N-geneous assay (96.1 ± 21.2 mg/dl), or the glucose, triacylglycerol, total cholesterol, or HDL-cholesterol level, but LDL-cholesterol levels evaluated from the Friedewald equation (92.6 ± 20.3 mg/dl) became significantly lower. A fasting time longer than 12 h is not necessary to obtain reasonable blood lipid levels. The Friedewald equation gave higher LDL-cholesterol levels than N-geneous assay in young Japanese females who had eaten a low-energy meal, and lower values when they had eaten a high-energy meal. Thus, it may be necessary to pay attention to energy of nigh meal prior to blood withdrawal.

Detecting alterations of glucose and lipid components in human serum by near-infrared Raman spectroscopy

“…The LDL was calculated using the Friedewald equation: LDL = CHL -HDL -TRG/5 (Fukuyama et al, 2008). In patients with hypertriglyceridemia (TRG > 400 mg/dL) the LDL was measured directly in the plasma, given the inaccuracy of the equation for this case.…”

Matsuda–DeFronzo insulin sensitivity index is a better predictor than HOMA-IR of hypertension in Japanese: the Tanno–Sobetsu study

“…An additional 10 subjects whose serum TG level at the baseline examination was 4400 mg dl À1 were excluded, because that level of TG makes calculation of low-density lipoprotein cholesterol (LDL-C) concentration, by use of the Friedewald equation, invalid. 39 After the exclusion, 740 subjects remained and their data were used for crosssectional analyses in the present study.…”

Low-density lipoprotein cholesterol levels in adults with type 2 diabetes: An alternative equation for accurate estimation and improved cardiovascular risk classification

“…9,10 Most landmark clinical trials use an indirect estimation of LDL-C using the Friedewald formula, 11 which assumes a constant relationship between very-low-density lipoprotein cholesterol (VLDL-C) and triglycerides (TGs) (up to 4.5 mmol/L). 11,12 Together with its simplicity and low cost, the Friedewald formula also has good correlation with measured LDL-C (M-LDL-C) in patients with desirable TG levels. 13,14 However, this formula has imitations including the need for fasting and the reduced reliability of the calculation when plasma TG exceeds 4.5 mmol/L, as the presence of chylomicrons or intermediate density lipoprotein (IDL) may result in overestimation of VLDL-C, consequently underestimating LDL-C. 15 Assessment of LDL-C by using this formula, in clinical pathologies associated with these abnormalities in lipoprotein composition, for example, in alcoholism, dysbetalipoproteinemia and type 2 diabetes mellitus (T2DM), 16,17 may thus result in inaccuracies.…”