Friedewald Formula Research Articles

Apolipoprotein B Is a Good Tool for Screening Dyslipidaemia in Apparently Healthy Population

Dyslipidaemia is the major risk factor for cardiovascular disease (CVD) which is the leading cause of death in the world. Even though several lipid parameters are used, currently apolipoprotein B (apoB) is considered as the best predictor of CVD. Thus this study was carried out to find out the association between conventional lipid parameters and apoB in apparently healthy subjects. A descriptive cross-sectional study was carried out in 170 apparently healthy volunteers who were not diagnosed with dyslipidaemia. After 12 hours overnight fast venous blood was obtained and Total cholesterol (TC), Triglyceride (TG), High density lipoprotein cholesterol (HDL-C) were measured by enzymatic kit method. Low density lipoprotein cholesterol (LDL-C) was calculated by Friedewald formula and apoB was analyzed by immune turbid metry using a Konelab® auto analyzer. Among the participants, majority (63.5%) were females. The mean value of apoB concentration of the population was 103 ± 42 mg/dL which was similar and not significantly different between the genders (Males, 102 ± 37 mg/dL and Females, 104 ± 45 mg/dL). All lipid parameters showed a positive correlation with apoB concentration whereas HDL-C had a negative correlation (r = -0.165). HDL-C significantly (p < 0.05) decreased with increase in apoB concentration while LDL-C, TC/HDL-C and non-HDL-C significantly (p < 0.05) increased with an increase in apoB concentration. Present study suggests that serum apoB has better correlations and associations with the parameters that are used in conventional lipid profile and with markers recommended for diagnosing dyslipidaemia. Hence apoB could be used as a single marker for screening dyslipidaemia in apparently healthy people.

Comparison of LDL-Cholesterol Estimate using Various Formulae with Directly Measured LDL-Cholesterol in Indian Population.

Low-Density Lipoprotein Cholesterol (LDLc) is widely recognized as an established cardiovascular risk marker. Different formulae have been proposed for calculation of LDLc but have not been validated in Indian population and over a wide range of Triglycerides (TG). Friedewald formula is most commonly used which has various shortcomings. To calculate LDLc using various formulae and compare it with directly measured LDLc at various ranges of TG concentration in Indian population. One year lipid profile data of 21,503 samples was taken. Calculation of LDLc was done by the following formulae: Friedewald; Cordova and Cordova; Vujovic; Ahmadi; Anandaraja; Puavillai and Hattori. Comparison of calculated LDLc with directly measured LDLc was done at following TG ranges: <150mg/dL; 151-199mg/dL; 200-399mg/dL and >400mg/dL using Pearson's correlation coefficient and two-paired t-test. For TG range <150mg/dL, Puavillai formula correlated best with direct measurement (r = 0.978). For TG range 151-199mg/dL, Vujovic formula correlated best with direct measurement (r = 0.977and mean difference of -1.2 mg/dL). For TG range 200-399mg/dL, Vujovic formula correlated best with direct measurement (r = 0.968). For TG range >400 mg/dL, Vujovic formula correlated best with direct measurement (r = 0.791). Vujovic formula appears to be more accurate than any other formula when applied to Indian population.

Effect of centrifuge test on blood serum lipids index of cadet pilots

This study aimed at investigating the relationship between the lipid index (WS) in the examined cadets and duration of exposure to +Gz in the human centrifuge. The study involved 19 first-year cadets of the Polish Air Force Academy in Dęblin. Tests in the human centrifuge were repeated twice, i.e. prior to (test I) and 45 days after (test II). After exposure to +Gz, the examined cadets were divided into 2 groups. Group I (N=11) included cadets subjected to a shorter total duration of exposure to +Gz, while group II (N=8) included cadets with a longer total duration of exposure to +Gz. Total cholesterol (TC), high density lipoprotein (HDL), triglycerides (TG), and apolipoproteins A1 and B were assayed in blood serum prior to (assay A) and after (assay B) both exposures to +Gz. Low density lipoprotein (LDL) level was estimated from the Friedewald formula. WS is an own mathematical algorithm. WS was higher in group II, assay A - 10.0 and B - 10.08 of test I in the human centrifuge than in group I where the WS values were 6.91 and 6.96, respectively. WS was also higher in group II in assay A - 10.0 and B -10.1 of test II in the human centrifuge than in group I - 6.96 and 6.80, respectively. The higher value of WS in group II, both after the first and second exposure to +Gz in human centrifuge, in comparison with group I, indicated its usefulness for determination of the maximum capability of applying acceleration of the interval type during training in the human centrifuge.

Lipid profile in type 2 diabetic subjects aged 40 years and over living in Benin

Background : Abnormal lipid profile is common in subjects with type 2 diabetes (T2D). Despite use of lipid-lowering agents, many subjects with T2D do not achieve lipid targets. The present work aimed to assess lipid profile in a randomly selected group of adult diabetic subjects under treatment in order to determine how diabetes treatment affects blood lipid parameters levels. HbA1c level is used as a biomarker of glycaemia control achievement and treatment success in diabetic. Methods : This study was carried out as a pre-post test design study with a control group. A total of 117 diabetic subjects under treatment and 100 non-diabetics as control subjects are included in the study. CT, TG and HDL-C were measured by enzymatic methods and LDL-C was determined by Friedewald formula. Plasma glucose was measured by Glucose Oxidase method and glycated hemoglobin (HbA1c) with a radioimmunoassay. Results : The results showed that CT (p 7.0% had significantly higher levels of TC (P 7.0%. Abnormal lipid patterns and insulin resistance tend to be normalized with therapy of diabetes.

Comparison of LDL- Cholesterol Enzymatic Method with Friedewald’s Formula

Background and Objective: Concentration low-density lipoprotein (LDL) is one of the strongest indicators of atherosclerosis and predicts the diagnosis of cardiovascular diseases. LDL measurement accuracy is very important. LDL can be measured directly, such as enzymatic and nephelometry methods or can be calculated using Friedewald's formula. Despite the development of enzymatic methods and LDL nephelometry still in most laboratories is calculated using Friedewald's formula. The aim of this study was an investigation of correlation coefficient between two methods of measuring LDLcholesterol levels. Methods: This descriptive cross-sectional study, performed on the 1141 patients. Cholesterol, triglycerides, HDL, LDL all patients assayed by enzymatic method. For patients with triglyceride levels of less than 400 mg/dl had LDL levels were calculated by Friedewald's formula. Normal levels of LDL/HDL ratio of less than 3.5 were considered. Results: Of the 1141 patients participating in this study, 38.3 % men and 61.7 % women. The mean patient age was 46.3 ± 16.1 years. Mean serum cholesterol, triglycerides and HDL were 177.9 ± 41.1, 132.9 ± 73.2 and 45.8 ± 13.2 mg/dl, respectively. Average direct and calculated LDL concentration was 82.1 ± 23.1 and 105.5 ± 35.8, respectively. The direct measurement of LDL, LDL/HDL levels in 97.1% of cases was normal, while 85.1 % of the calculation of LDL were normal. Pearson correlation coefficients were obtained by two methods:

LDL-콜레스테롤의 Friedewald 계산값과 실측값 비교: 국민건강영양조사 2009-2010

Low-density lipoprotein cholesterol (LDL-C) is a major modifiable risk factor for cardio- cerebrovascular disease. In clinical practice, however, it is primarily calculated using the Friedewald formula as a cost-effective method. The aim of this study was to compare Friedewald-estimated and directly measured LDL-C values and assess the concordance in guideline LDL-C risk classification between the two methods. The data were derived from the 2009 and 2010 Korea National Health and Nutrition Survey (KNHANES). Analysis was done for 4,319 subjects with lipid panels-total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), directly measured LDL-C using an enzymatic homogeneous assay, and triglycerides (TG). For subjects with TG lower than 400 mg/dL, Friedewald-estimated and directly measured LDL-C were highly correlated (r = 0.958, p . As a result, Friedewald estimation misclassified 382 subjects (9.1%) in a higher category versus 348 subjects (8.3%) in a lower category. Our findings suggest that overestimation of LDL-C by the Friedewald formula can be a great problem as well as underestimation.

Alcohol Dehydrogenase-1B (rs1229984) and Aldehyde Dehydrogenase-2 (rs671) Genotypes Are Strong Determinants of the Serum Triglyceride and Cholesterol Levels of Japanese Alcoholic Men.

BackgroundElevated serum triglyceride (TG) and high-density-lipoprotein cholesterol (HDL-C) levels are common in drinkers. The fast-metabolizing alcohol dehydrogenase-1B encoded by the ADH1B*2 allele (vs. ADH1B*1/*1 genotype) and inactive aldehyde dehydrogenase-2 encoded by the ALDH2*2 allele (vs. ALDH2*1/*1 genotype) modify ethanol metabolism and are prevalent (≈90% and ≈40%, respectively) in East Asians. We attempted to evaluate the associations between the ADH1B and ALDH2 genotypes and lipid levels in alcoholics.MethodsThe population consisted of 1806 Japanese alcoholic men (≥40 years) who had undergone ADH1B and ALDH2 genotyping and whose serum TG, total cholesterol, and HDL-C levels in the fasting state had been measured within 3 days after admission.ResultsHigh serum levels of TG (≥150 mg/dl), HDL-C (>80 mg/dl), and low-density-lipoprotein cholesterol (LDL-C calculated by the Friedewald formula ≥140 mg/dl) were observed in 24.3%, 16.8%, and 15.6%, respectively, of the subjects. Diabetes, cirrhosis, smoking, and body mass index (BMI) affected the serum lipid levels. Multivariate analysis revealed that the presence of the ADH1B*2 allele and the active ALDH2*1/*1 genotype increased the odds ratio (OR; 95% confidence interval) for a high TG level (2.22 [1.67–2.94] and 1.39 [0.99–1.96], respectively), and decreased the OR for a high HDL-C level (0.37 [0.28–0.49] and 0.51 [0.37–0.69], respectively). The presence of the ADH1B*2 allele decreased the OR for a high LDL-C level (0.60 [0.45–0.80]). The ADH1B*2 plus ALDH2*1/*1 combination yielded the highest ORs for high TG levels and lowest OR for a high HDL-C level. The genotype effects were more prominent in relation to the higher levels of TG (≥220 mg/dl) and HDL-C (≥100 mg/dl).ConclusionsThe fast-metabolizing ADH1B and active ALDH2, and especially a combination of the two were strongly associated with higher serum TG levels and lower serum HDL-C levels of alcoholics. The fast-metabolizing ADH1B was associated with lower serum LDL-C levels.

Association between Lipid Profile and Ovarian Cancer in women of North India

Objective: The aim of this study was to compare serum lipid profiles: total cholesterol (TC), triglyceride (TG), high density lipoprotein cholesterol (HDL-c), low density lipoprotein cholesterol (LDL-c) and very low density lipoprotein cholesterol (VLDL-c) and lipid ratio among ovarian cancer (OC) patients and healthy controls. Methods: Total 300 subjects were enrolled in this study. Study group comprised of 150 clinically and histologically proved cases of ovarian carcinoma and 150 healthy women recruited as a control group. Plasma levels of TC, TG and HDL were determined using a commercially available kit and a semi-automated analyzer. LDL and VLDL were calculated by Friedewald's formula. Results: In our study, we found the higher level of mean serum cholesterol, TGs, LDL-c and VLDL in OC patients as compared to the controls. The HDL level is higher in controls as compared to study group. TGs, HDL-c VLDL were found highly significant in OC patients as compared to controls. The Ratio of TC/HDL, LDL/HDL, HDL/LDL was also found significantly higher in OC patients as compared to controls. Conclusions: The results of the present study shows that plasma lipid levels, except HDL-cholesterol, are increase in OC. As there is an alteration in the plasma lipid profile during gynecologic cancers, it may be helpful for diagnosis of the disease. Further studies needed to investigate, to group important factors including, cancer stages and type of cancer, parity, and menopausal status that may affect lipid profiles in OC patients along with an investigation of new lipid profiles to clarify most lipid factors that may involve in OC development are needed.

Evaluation of Recently Developed Regression Equation with Direct Measurement of Low-density Lipoprotein Cholesterol in a Bangladeshi Population

Background: Meaningful underestimation of low-density lipoprotein (LDL) cholesterol is an important shortcoming of Friedewald’s formula (FF) at higher triglyceride (TG) levels. Recently a regression equation (RE) has been developed using lipid profiles in one setting and validated externally for the calculation of LDL cholesterol. This newly developed RE requires more studies in different settings.Objective: The aim of this study was to evaluate the performance of the regression equation against direct measurement.Materials and Methods: Lipid profiles of 600 subjects attending a tertiary healthcare center were included in this study. Specimens were collected and lipid profiles were measured by standard methods. Sixty two lipid profiles with TG above 400 mg/dL were excluded. Calculated LDL cholesterol values using FF and RE were compared with measured LDL cholesterol by Pearson’s correlation test, Passing &amp; Bablok regression, accuracy within ±5% and ±12% of measured LDL cholesterol and two-tailed paired t test at various TG ranges.Results: The mean value of LDL cholesterol was 148.6 ± 37.2 mg/dL for direct measurement, 146.9 ± 42.4 mg/dL for FF and 148.6 ± 34.7 mg/dL for RE. The correlation coefficients of calculated LDL cholesterol values with measured LDL cholesterol were 0.949 (p&lt;0.001) for FF and 0.959 (p&lt;0.001) for RE. Passing &amp; Bablok regression equation against measured LDL cholesterol was y = 0.897x + 16.2 for FF and y = 1.0842x – 13.1 for RE. Accuracy within ±5% of measured LDL cholesterol was 45% for FF, 57% for RE and within ±12% of measured LDL cholesterol was 84% for FF, 93% for RE. When calculated LDL cholesterol was compared with measured LDL cholesterol at different TG ranges, FF significantly underestimated LDL cholesterol at TG concentrations above 200 mg/dL whereas no significant difference was observed for RE.Conclusion: This study reveals that RE equation has similar performance to direct measurement for calculation of LDL cholesterolJ Enam Med Col 2015; 5(2): 75-79

Abstract 469: Relationship of Heart Rate and Physical Activity with Cardiovascular Risk Factors in a Multi-ethnic Population.

Introduction: Resting heart rate (RHR) has been identified as an independent risk factor for cardiovascular disease and mortality. Hypothesis: Physical activity and RHR are associated with hypertension, dyslipidemia and insulin resistance in a multiethnic population. Methods: Cross-sectional data from 1,440 participants of Native Hawaiian, Japanese, Filipino, Caucasian, and mixed ethnic ancestries were examined. Body fat was estimated using body mass indices (BMI); fat distribution by waist-hip ratios (WHR); and insulin resistance using the Homeostasis Model (HOMA-IR). Total cholesterol, triglycerides, and HDL-cholesterol levels were assayed from fasting plasma samples. LDL cholesterol was calculated using the Friedewald formula. Blood pressure measurements and medical histories were obtained to determine hypertension status. Leisure time physical activity (PA) was estimated by calculating metabolic equivalents (METS) using the Modifiable Activity Questionnaire. Associations were estimated using logistic regression for dichotomous outcomes (HTN) and general linear models (GLM) for continuous variables. Results: Caucasians had lower prevalence of HBP and insulin resistance than all other ethnic groups; there were no statistically significant differences between other ethnic groups on mean RHR. HOMA-IR, RHR, BMI and WHR all differed significantly by ethnic group. Low RHR and high levels of physical activity were inversely associated with insulin resistance. After adjusting for covariates, only RHR remained significantly associated with HBP prevalence. Likewise, only RHR was significantly associated with total cholesterol, LDL and triglycerides. In contrast, HDL cholesterol was positively associated with physical activity but not associated with RHR. Conclusion: The relationship of RHR and PA is complex with RHR and PA actions differing for different CVD risk factors. Since low RHR may be an indicator of cardiovascular fitness, these findings suggest fitness, rather than energy expenditure, may be important in preventing most CVD risk factors, while activity level may be more important for increasing HDL levels. A customized approach to activity plans may need to consider specific patient risk profiles.

Effect of serum triglycerides on LDL estimation by Friedewald formula and direct assay: a laboratory based study

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.

Validation of the Friedewald Formula in Type II diabetes mellitus : An Indian perspective study

Introduction: Diabetes mellitus is characterized by hypertriglyceridemia and abnormal lipoprotein composition. Since LDL is a modifiable risk factor for cardiovascular complications in diabetes, its measurement is recommended in routine clinical practice. Objective of the study is to assess the accuracy of serum LDL concentration estimation by Friedewald formula and by homogenous method in normal and diabetic patients. Materials and Methods: Fasting blood samples were collected from 300 subjects (109 normal persons 101prediabetics, 90 diabetics). Glucose, total cholesterol, LDL and HDL were estimated spectrophotometrically and LDL was calculated by Friedewald formula. LDL calculated by Friedewald formula was compared with that obtained by direct assay. Results: LDL determined by direct assay correlated highly with calculated LDL in all subjects irrespective of fasting glucose value. Estimated LDL was higher than calculated LDL in normal and diabetic group, indicating the fact that calculated LDL underestimates the true LDL levels irrespective of fasting glucose levels. Further, the difference in the means were significantly high in all the 3 groups with significance being highest in the diabetic group (p<0.001) Conclusion: it can be concluded that estimation of LDL is always a better investigation technique than following calculations for LDL estimation, considering the importance of patient care in treatment of lipid disorders in diabetes mellitus.

Comparison of equations for the calculation of LDL-cholesterol in hospitalized patients

BackgroundThe Friedewald equation is widely used to calculate LDL-C for cardiovascular risk prediction but is less accurate with comorbidities and extreme lipid values. Several novel formulae have been reported to outperform the Friedewald formula. MethodsWe examined 14,219 lipid profiles and evaluated four formulae (Friedewald, Chen, de Cordova, Hattori) and compared these to direct measurement of LDL-C across various triglyceride (TG), total cholesterol (TC) and HDL-cholesterol (HDL-C) ranges using Beckman reagents and instruments. Linear regression and ROC analysis were performed. ResultsThe de Cordova formula showed a high correlation with directly measured LDL-C (r=0.90, P<0.001), comparable to the Friedewald calculated values for directly measured LDL-C (r=0.95, P<0.001). The de Cordova formula was favorable in some ranges of HDL, TC and the lowest TG range (r=0.97, P<0.001) but performed least well in comparison with the three other LDL-C calculations (AUC=0.8331), demonstrating inconsistent bias. The Chen formula performed better than Friedewald (AUC=0.9049). The Hattori formula outperformed all formulae including Friedewald over various ranges of lipid values (AUC=0.9097). ConclusionsWe observe favorable correlations of the de Cordova formula with Friedewald at low TG values. However, the Hattori formula appears to be best for application in hospitalized patients, even at extreme lipid values.

Evaluation of the Novel Method and the Regression Equation for Calculation of Low-Density Lipoprotein Cholesterol

Background: Friedewald’s formula (FF) is used worldwide to calculate low-density lipoprotein cholesterol (LDL-chol). But it has several shortcomings: overestimation at lower triglyceride (TG) concentrations and underestimation at higher concentrations. In FF, TG to very low-density lipoprotein cholesterol (VLDL-chol) ratio (TG/VLDL-chol) is considered as constant, but practically it is not a fixed value. Recently, by analyzing lipid profiles in a large population, continuously adjustable values of TG/VLDL-chol were used to derive a novel method (NM) for the calculation of LDL-chol. Objective: The aim of this study was to evaluate the performance of the novel method compared with direct measurement and regression equation (RE) developed for Bangladeshi population. Materials and Methods: In this cross-sectional comparative study we used lipid profiles of 955 adult Bangladeshi subjects. Total cholesterol (TC), TG, HDL-chol and LDL-chol were measured by direct methods using automation. LDL-chol was also calculated by NM and RE. LDL-chol calculated by NM and RE were compared with measured LDL-chol by twotailed paired t test, Pearson’s correlation test, bias against measured LDL-chol by Bland-Altman test, accuracy within ±5% and ±12% of measured LDL-chol and by inter-rater agreements with measured LDL-chol at different cut-off values. Results: The mean values of LDL-chol were 110.7 ± 32.0 mg/dL for direct measurement, 111.9 ± 34.8 mg/dL for NM and 113.2 ± 31.7 mg/dL for RE. Mean values of calculated LDL-chol by both NM and RE differed from that of measured LDL-chol (p&lt;0.01 for NM and p&lt;0.0001 for RE). The correlation coefficients of calculated LDL-chol values with measured LDL-chol were 0.944 (p&lt;0.0001) for NM and 0.945 (p&lt;0.0001) for RE. Bland- Altman plots showed good agreement between calculated and measured LDL-chol. Accuracy within ±5% of measured LDL-chol was 49% for NM, 46% for RE and within ±12% of measured LDL-chol was 79% for both NM and RE. Inter-rater agreements (?) between calculated and measured LDL-chol at LDL-chol &lt;100 mg/dL, 100–130 mg/dL and &gt;130 mg/dL were 0.816 vs 0.815, 0.637 vs 0.649 and 0.791 vs 0.791 for NM and RE respectively. Conclusion: This study reveals that NM and RE developed for Bangladeshi population have similar performance and can be used for the calculation of LDL-chol. DOI: http://dx.doi.org/10.3329/jemc.v5i1.21491 J Enam Med Col 2015; 5(1): 10-14

A new formula for estimation of low-density lipoprotein cholesterol in an ethnic Chinese population

Low-density lipoprotein cholesterol (LDL-C) is an established risk factor for cardiovascular disease and is usually estimated by the Friedewald formula (FF) calculated from three parameters, namely, total cholesterol (TC), triglyceride (TG), and high-density lipoprotein cholesterol (HDL-C). We aimed to develop a new and simple formula (NF) for LDL-C estimation. This cross-sectional study enrolled two study populations (a testing group, n=16,749, and a validation group, n=4940). Linear regression analysis was used in the testing group to investigate the association between measured LDL-C (mLDL-C) and TC concentration, and was verified in the validation group. The NF yielded an estimated LDL-C (eLDL-C) equal to 0.75 × total cholesterol-0.6465 (mmol/L). For the subjects with TC between 2.58 and 7.74 mmol/L, the difference between mLDL-C and eLDL-C using the NF was less than that from the FF (testing group: -0.04 to -0.20 vs. -0.28 to -0.38 mmol/L; validation group: 0.01 to -0.12 vs. -0.23 to -0.30 mmol/L; p<0.001, respectively). The predictability of the NF was not inferior to that of the FF in subjects with different triglyceride and HDL-C concentrations, and was not affected by diabetes diagnosis and statin use. However, the NF performed similar to or worse than the FF at TC concentrations <2.58 mmol/L and >7.74 mmol/L, respectively. In the Chinese population, the accuracy of eLDL-C measurement with the NF was better than that with the FF, especially in subjects with TC levels between 2.58 and 7.74 mmol/L. The NF is simple and may be used for screening as well as for follow-up of patients on lipid lowering agents.

A Comparative Study of Methods of Estimation of LDL-Cholesterol: Direct vs Friedewald's Formula and Their Impact on the Risk Assessment for Coronary Artery Diseases

Coronary artery disease is one of the leading causes of mortality and morbidity worldwide. Correct estimation of low density lipoprotein (LDL) cholesterol is not only fundamental but also imperative towards the right diagnosis, risk assessment and management of the patients of cardiac diseases. Many laboratories rely on the calculated method of LDL-C estimation. Direct assays are now replacing the calculated methods owing to some of the limitations of the latter. We carried out a comparative study to evaluate the reliability of both the methods and their impact on assessing cardiac risk. Fasting lipid profile (including TG, Total Cholesterol, LDL-C and HDL-C) was measured by direct enzymatic assays in serum samples of 200 patients who visited the Biochemistry Laboratory for this test. LDL-C was also estimated by Friedewald's formula. Results of LDL-C obtained by two methods were compared and statistically analysed. We found a significant positive correlation between the values of LDL-C obtained by two methods i.e. Friedewald's formula and Direct Assay. Friedewald's formula underestimated the actual LDL-C levels especially when the serum TG levels were high and this difference was significant when the TG levels were >400 mg/dL. Thus, some of our patients who were having high cardiac risk (LDL-C >130 mg/dL) were misdiagnosed to be normal. Friedewald's formula can be used for LDL-C estimation when TG levels are in the normal range but results become doubtful especially when the serum TG levels are high. Direct assay has an advantage that it is not influenced by the concordant serum TG concentrations and can be relied upon confidently in determining cardiac risks in the individuals.

Assessing the Validity of Friedewald's Formula and Anandraja's Formula For Serum LDL-Cholesterol Calculation.

An important aspect of the assessment of cardiovascular risk for a dyslipidemic subject is the estimation of serum Low-Density Lipoprotein Cholesterol (LDL-C). 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) - (TG/5). Recently Anandaraja and colleagues have derived a new formula for calculating LDL-C, AR-LDL-C = 0.9 TC- (0.9 TG/5)-28. The aim of the study was: a) to determine if, and to what extent, LDL-C level was underestimated/overestimated when it was calculated using the formulae compared with direct measurement of LDL-C, and b) to determine which of the calculated formulae show maximum correlation with direct LDL cholesterol method at different TG levels. A cross-sectional study. Record analysis was done from the 370 (TG <400mg/dl) lipid profile reports of patients above 18 years. LDL-C estimation was done by homogenous assay and also calculated using the Friedewald's Formula and Anandaraja's Formula. The mean LDL-C levels were 105.17± 43.4, 102.98 ±42.5, and 98.20 ±43.7 mg/dl for D-LDL-C, F-LDL-C and AR-LDL-C, respectively. A good correlation was found between the calculated LDL-C methods and Direct Low-Density Lipoprotein Cholesterol method (D-LDL-C) assay, that is, F-LDL-C versus D-LDL-C (r = 0.937) and AR-LDL-C versus D-LDL-C (r= 0.918). Bland-Altman plot for FF-LDL-C & AR-LDL-C showed minimal negative bias. FF-LDL-C correlated maximally with D-LDL-C estimation at all levels of triglycerides except at TG < 100mg/dl. At TG < 100mg/dl, Anandaraja's Formula works better. FF-LDL-C can be used in place of D-LDL-C when the direct method cannot be afforded.

Evaluation of High-Sensitivity C-Reactive Protein and Serum Lipid Profile in Southeastern Nigerian Women with Pre-Eclampsia

Objective: To evaluate the serum C-reactive protein (CRP) and lipid profile in women with pre-eclampsia. Materials and Methods: Thirty-five women with and 35 women without pre-eclampsia, who were in the 3rd trimester of pregnancy, were enrolled in this study. Weight in kilogrammes and height in metres were measured to calculate the mean body mass index (BMI) for each group. The diastolic and systolic blood pressures were measured. Lipid profile tests and serum CRP assay were done for all patients. Total cholesterol, triglycerides (TG) and high-density lipoprotein cholesterol (HDL-C) were determined using enzymatic methods, while low-density lipoprotein cholesterol (LDL-C) was calculated using Friedewald's formula. Results: The mean values of the BMI were 29.47 ± 6.90 versus 26.14 ± 2.92, of the diastolic blood pressure 109.14 ± 15.41 versus 72.29 ± 9.42 mm Hg and of the systolic blood pressure 170.57 ± 19.55 versus 120.86 ± 17.72 mm Hg for women with and without pre-eclampsia, respectively, and the differences were statistically significant (p = 0.012, p = 0.001 and p = 0.001, respectively). The biochemical analysis also indicated that the women with pre-eclampsia had a significantly higher mean serum CRP (8.57 ± 2.68 vs. 6.46 ± 2.46 mg/l, p = 0.001), TG (2.84 ± 0.45 vs. 1.87 ± 0.38 mmol/l, p = 0.001) and total cholesterol (5.59 ± 0.92 vs. 4.63 ± 0.78 mmol/l, p = 0.001) level but a lower mean HDL-C (1.10 ± 0.12 vs. 1.26 ± 0.15 mmol/l, p = 0.001) level than the controls. There was no statistical difference in the mean LDL-C values between the 2 groups (1.58 ± 0.8 vs. 1.45 ± 0.78 mmol/l, p > 0.05). Conclusion: Significant changes in CRP as well as TG, total cholesterol and HDL-C were associated with pre-eclampsia in these Southeastern Nigerian women.

Blood Pressure is the Strongest Component Associated with Arterial Stiffness in Mexican Patients with Metabolic Syndrome

Objective: To establish which of the metabolic syndrome (MetS) components are more related to arterial stiffness. Research Design and Methods: We recruited eighty-two non-smoking male patients, 40 to 77 years old, (42 without MetS and 41 with MetS). The local ethics committee approved the study and signed informed consent forms were obtained from patients. Body mass index (BMI) was calculated as weight (in kilograms) divided by the square of height (in meters), and waist measurements were according to WHO recommendations. Blood pressure and baPWV were measured with the “Vascular Profiler 1000” device (VP-1000) (Omron®, Kyoto, Japan). All blood sample determinations were obtained after a 12-h fasting period and processed within one h. We used an oxidase technique to measure fasting plasma glucose (FPG) and enzymatic methods to obtain total cholesterol, high-density lipoprotein cholesterol (HDL-c) and triglyceride values. Low-density lipoprotein cholesterol (LDL-c) was estimated using the Friedewald formula (LDL-C = Total Cholesterol − HDL-C − Triglycerides/5). Results: We observed strong and significant correlations between SBP and baPWV (r=.753, p=&lt;0.001), and between SBP and PP (r=.853, p=&lt;0.001). The remaining components did not correlate with baPWV or PP.

Measuring Low Density Lipoprotein Cholesterol: Comparison of Direct Measurement by HiSens Reagents and Friedewald Estimation.

BackgroundDirectly measured low density lipoprotein cholesterol (DLDLC) has been reported to be more accurate than calculated low density lipoprotein cholesterol (CLDLC) using the Friedewald equation. However, some limitations of DLDLC have been reported. In this study, we evaluated differences between CLDLC and DLDLC measured using HiSens reagents.MethodsData were collected from 582 persons undergoing routine physical examinations at a general hospital. LDLC measurements were made directly or estimated using the Friedewald formula, and were classified according to the National Cholesterol Education Program's Adult Treatment Panel III guidelines. The relationship between these differences and other clinically relevant factors, such as triglyceride (TG) levels, were examined using multiple logistic regression analysis.ResultsThe DLDLC and CLDLC were strongly correlated according to simple linear regression analysis (r=0.917, P<0.001) but the mean difference between measurements was -11.0±15.3 (-62 to 90.5) mg/dL (P<0.001). For more than 10 mg/dL of their absolute differences, the DLDLC was typically lower than the CLDLC. The highest discrepancies in LDLC measurements occurred when LDLC was more than 160 mg/dL and less than 190 mg/dL. Differences in LDLC measurements were prone to striking negative and positive biases dependent on CLDLC and TG concentrations, respectively (all r>0.5).ConclusionUnlike other studies, DLDLC was significantly lower than CLDLC and the large differences in LDLC concentrations were not dependent on TG concentration. Our work suggests that verification of DLDLC accuracy is needed and differences in LDLC measurements should be accounted for in making clinical decisions.