Is direct method of low density lipoprotein cholesterol measurement appropriate for targeting lipid lowering therapy? (original) (raw)
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Estimation of low density lipoprotein cholesterol (LDL-C) level in serum is considered to be the basis of classification and management of hypercholesterolemia. In most clinical laboratories, LDL-C is usually estimated indirectly with the Friedewald's equation or more accurately with direct methods. The lack of agreement between the two methods has been reported in several clinical laboratories using different methods. The present study is designed to compare LDL-cholesterol values obtained by Friedewald's formula and a direct method available in our laboratory (Dimension, RxL, and SIEMENS). In the present study, we have found no significant differences between LDL-C obtained by Friedewald's formula (94.49 mg/dl ±28.81) and those determined by the direct method (93.98 mg/dl ±27.77) from samples with TG levels at <100 mg/dl (p>0.4) with correlation coefficient of 0.86. The LDL-C levels produced by Friedewald's formula were significantly lower than those obtained by the direct method when serum TG levels at 101-200 mg/dl (p <0.001) and 201-300 mg/dl (p <0.01) with correlation coefficient of 0.96 and 0.97 respectively. These differences are in agreement with those previously reported results in other laboratories. Therefore Friedewald's formula must be replaced by the direct method for better classification and management of hypercholesterolemia.
Comparison of LDL -cholesterol estimated by direct method and by calculation
Introduction: Total cholesterol (TC) and Low-density lipoprotein cholesterol (LDL-C) are well-established risk factors for the coronary heart disease (CHD). There are many homogenous assays currently available for the estimation of serum LDL-C. Most clinical laboratories determine LDL-C (mg/dL) by Friedewald's formula (FF), LDL-C = (TC)-(HDL-C)-(TAG/5). This formula shows the level of LDL-C is dependent on triglyceride (TAG) level. Aim and Objectives: The aim of this study was to find out the relative advantages of direct measurement of cholesterol over the conventional derivation of LDL-C by calculation. Material and Method: The study contained 80 participants above 18 years. LDL-C estimation was done by direct method manually on the spectrophotometer and also calculated using the Friedewald's Formula. An independent t-test was applied to find out the statistically significant difference. Results: It was observed that, the mean LDL-C levels by calculated method and the direct method in the control group (TAG≤150 mg/dl) (114.83 and 116.88 mg/dl respectively, P=0.81), case group-1 (TAG=150-300 mg/dl) (113.11and 116.01 mg/dl respectively, P=0.82) and case group-2 (TAG=300-400 mg/dl) (112.75and 116.30 mg/dl respectively, P=0.73) show no significant difference, but in the case group-3 (TAG≥400 mg/dl) (112.12 and 182.0 mg/dl respectively, P<0.001) shows significant difference. Conclusion: Our data suggest that; the estimated LDL-C can be substantially underestimated due to the high triglyceride levels of 400 mg/dl or more. These results in the misclassification of the risk, where the patient's calculated LDL-C may be lower than their true LDL-C, resulting in the missed opportunities for the treatment.
Arquivos brasileiros de cardiologia, 2004
To compare direct measurement of LDL-cholesterol (LDL-C) determined by a homogeneous method with LDL-cholesterol estimation determined by the Friedewald formula in a large heterogeneous population. The measurements of total cholesterol (TC) and triglycerides (TG) were performed using traditional enzymatic methods. The measurements of HDL-C and LDL-C were performed using direct methods with no precipitation, and the estimation of the LDL-C fraction was calculated using the Friedewald formula. On linear regression analysis, the 2 methods had extremely significant correlation coefficients (P < 0.001). However, the Friedewald formula had a positive bias in regard to the direct method, more pronounced with TC levels > 201 mg/dL. This positive bias also occurred in regard to TG levels < or =150 mg/dL. No bias was observed between the methods for TG levels ranging from 151 to 200 mg/dL and from 201 to 300 mg/dL. On the other hand, for TG levels ranging from 301 to 400 mg/dL, this ...
Medical Journal of Shree Birendra Hospital, 2016
Introduction: Estimation of low density lipoprotein cholesterol (LDL-C) is crucial in management of coronary artery disease patients. The management of dyslipidemia is largely based on the concentration of LDL-C. The objective of this study was to compare direct measurement of LDL-C determined by a homogenous method with LDL-C estimation done by Friedewald formula (FF) in heterogeneous populations. Methods: In this cross sectional study, we measured LDL-C by homogenous method (D-LDL-C) in 1,000 fasting samples & compared with FF (F–LDL-C) used for calculation of LDL-C. The measurements of total cholesterol (TC) and triglycerides (TG) were performed using traditional enzymatic methods. The measurements of high density lipoprotein cholesterol (HDL-C) and LDL-C were performed using direct methods with precipitation, and the estimation of the LDL-C fraction was calculated using the FF. Results: Correlation analysis shows that the two methods had significant correlation (p<0.0001). Ho...
Method of LDL Cholesterol Measurement Influences Classification of LDL Cholesterol Treatment Goals
Journal of Investigative Medicine, 2010
Background-Low density lipoprotein cholesterol (LDL-C) has been clearly associated with the risk of developing coronary heart disease (CHD). The best and most convenient method for determining LDL-C has come under increased scrutiny in recent years. We present comparisons of Friedewald's calculated LDL-C (C-LDL-C) and direct LDL-C (D-LDL-C) using three different homogenous assays. This highlights differences between the two methods of LDL-C measurement, and how this affects the classification of samples into different LDL-C treatment goals as determined by NCEP ATP III guidelines thus potentially affecting treatment strategies. Methods-Lipid profiles of a total of 2,208 clinic patients were retrieved from the Central Arkansas VA Healthcare System (CAVHS) clinical laboratory database. Samples studied were of one week period of time during the 3 periods studied, 2000 (period 1), 2002 (period 2) and 2005 (period 3). Different homogenous assays for D-LDL-C measurement were used for each of the 3 periods.
Indian Journal of Clinical Biochemistry, 2005
Current recommendations of the Adult Treatment Panel and Adolescents Treatment Panel of National Cholesterol Education Program make the low-density lipoprotein cholesterol (LDL-C) levels in serum the basis of classification and management of hypercholesterolemia. A number of direct homogenous assays based on surfactant/ solubility principles have evolved in the recent past. This has made LDL-C estimation less cumbersome than the earlier used methods. Here we compared one of the direct homogenous assays with the widely used Friedewald's method of estimation of LDL-C to see the differences and correlation. We used direct homogenous assay kit to estimate serum LDL -C and high-density lipoprotein cholesterol (HDL-C). Serum Triglyceride (TG) and Total Cholesterol (TC) was estimated and using Friedewald's formula LDL -C was calculated. The LDL-C levels obtained by both methods in 893 fasting serum samples were compared. The statistical methods used were paired t-test and Pearson's correlation.
2016
Abstract: Estimation of low density lipoprotein cholesterol (LDL-C) level in serum is considered to be the basis of classification and management of hypercholesterolemia. In most clinical laboratories, LDL-C is usually estimated indirectly with the Friedewald’s equation or more accurately with direct methods. The lack of agreement between the two methods has been reported in several clinical laboratories using different methods. The present study is designed to compare LDL-cholesterol values obtained by Friedewald’s formula and a direct method available in our laboratory (Dimension, RxL, SIEMENS). In the present study, we have found no significant differences between LDL-C obtained by Friedewald’s formula (94.49 mg/dl ±28.81) and those determined by the direct method (93.98 mg/dl ±27.77) from samples with TG levels at <100 mg/dl (p>0.4) with correlation coefficient of 0.86. The LDL-C levels produced by Friedewald’s formula were significantly lower than those obtained by the di...
Assessment of various calculation methods for measurement of LDL-Cholesterol
2016
Background: Coronary Artery Disease is the leading cause of death worldwide and LDL has been recommended as the primary lipid subset for prediction of risk of CAD NCEP guidelines. Many assays have been developed for measurement of LDL levels and have shown reasonable accuracy as compared to reference method but still not cost effective and cannot be affordable by majority of laboratories. Laboratories use the cost effective Friedewald's formula for calculating the LDL instead of direct assay which give near to accurate value but has its own limitations. In recent days many newer formulae have come up with lesser limitations and here an attempt is made to evaluate these formulae and to correlate with direct measurement of LDL. Methodology: It's a cross sectional study. Sampling technique is Census method and involves sample size of 1020 cases. The entire lipid Parameters (LDL, HDL, TC, and TG) were estimated using Kits purchased by Roche /Cobas and then LDL also calculated using various formulae. Data was entered in Excel and analysed by Epi info software. Descriptive statistics like mean, standard deviation, standard error of mean were calculated. Student t test and Pearson's correlation are used to find the correlation between measured LDL and calculated LDL at different intervals of TG, TC and HDL. Results: A total of 1020 samples were studied. The Cordova Formula correlated well in all the 1000 samples as a whole and in subjects with normal lipid profile and also at all lipid levels except for TG < 200mg/dl, TC < 100mg/dl. At TG < 200mg/dl Anandaraja's formula shows better correlation and at TC < 100mg/dl none of the formulae performed well as all formulae negatively correlated with the direct measurement of LDL. Conclusion: Even though Cordova formula in our study has outperformed the other formulae, there are lots of factors which will affect the calculation. So it is highly recommended to switch to newer direct assays available in the market which are more precise, accurate, cost effective and also having low total allowable error < 12 and and a CV of <4%.
International Journal of Biomedical Research, 2015
Introduction: A long standing association exists between elevated serum LDL and cardiovascular disease. Studies have suggested that, increased LDL in serum is the major contributor to vascular complications of other diseases like diabetes mellitus, its measurement is recommended in routine clinical practice. Currently, estimation of LDL cholesterol is done in the clinical laboratories using Friedewald equation to make the lipid profile cost effective. However, it has been highlighted that calculated LDL is not reliable when serum triglyceride (TG) levels exceed 400mg/dl. Objective of the study: To compare estimated LDL by homogenous method with calculated LDL by Friedewald equation in lipid profile requests and to compare the same in different groups of triglyceride levels. Materials and Methods: About 260 lipid profile requests of both the genders aged between 25-75 years were considered for the study. Total cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol was estimated in the serum spectrophotometrically. LDL-C was also calculated using Freidewald formula. The Data thus collected was segregated based on triglycerides into three groups, Group I (TG ≤150mg/dl) Group II (TG 151-399 mg/dl) and Group III (TG ≥400 mg/dl). Results:LDL determined by direct assay correlated highly with calculated LDL in all subjects irrespective of the TG levels. Correlation coefficients being 0.96, 0.95 and 0.81 in group I, II and III respectively. Estimated LDL was significantlyhigher than the calculated LDL in group II and group III, suggestive of the fact that calculated LDL underestimates the true LDL levels in cases with TG levels above the normal range. Further, the differences in the means were significantly higher in hypertriglyceridemic groups (p < 0.001). Conclusion: it can be concluded that estimation of LDL needs a better accurate measurement technique than following calculations, considering the importance of patient care in management of life style disorders, aimed at lowering serum LDL levels.
Innovative publication, 2016
Background: To compare the results obtained by direct homogenous assay for LDL-C to those obtained by Friedwalds and Anandrajas formulas with the assumption that the results obtained by direct assay are most accurate. This was a comparative study for the estimation of LDL-C using two different types of calculation formulas and direct estimation of LDL-C by homogenous method. Method: Serum Lipids and lipoproteins were measured in 505 fasting samples. Serum Total cholesterol was measured using CHOD-PAP method first described by Stadman on Siemens Dimensions Clinical Chemistry RXL Analyzer. Triglycerides were measured by Glycerol Phosphate peroxidase-PAP method. Direct LDL-C was measured by a homogenous assay by siemens diagnostics. A-HDL was measured by a homogenous method which uses PEG-cholesterol esterase using kit from siemens diagnostics. This was a comparative study for the estimation of LDL-C using two different types of calculation formulas and direct estimation of LDL-C by homogenous method. Results: A good correlation was found between D-LDL as compared to both F-LDL and A-LDL. Pearsons coefficient of correlation between F-LDL & D-LDL was 0.891 (p<0.001) which was comparatively better than that between A-LDL & D-LDL which came out to be 0.850. Conclusion: In conclusion, regarding patients convenience, financial reasons and accuracy we support the reliability of Anandrajas formula as indirect low density lipoprotein estimation – in Punjabi population.