Research Article Validation of the Friedewald Formula in Patients with Metabolic Syndrome José Knopfholz, Caio César Diniz Disserol, Andressa Jardim Pierin, Fernanda Letícia Schirr, Larissa Streisky, Lilian Lumi Takito, Patrícia Massucheto Ledesma, José Rocha Faria-Neto, Marcia Olandoski, Claudio Leinig Pereira da Cunha, and Antonio Milton Bandeira Pontif´ ıcia Universidade Cat´ olica do Paran´ a, Rua Imaculada Conceic ¸˜ ao, Prado Velho, 1155 Curitiba, PR, Brazil Correspondence should be addressed to Caio C´ esar Diniz Disserol; cdisserol@gmail.com Received 16 September 2013; Revised 13 December 2013; Accepted 26 December 2013; Published 6 February 2014 Academic Editor: Gordon Ferns Copyright © 2014 Jos´ e Knopfolz et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Currently, the Friedewald formula (FF) is the main method for evaluating low-density lipoprotein cholesterol (LDL-c). Recently, many limitations have emerged regarding its use, including patients with triglyceride levels ≥400 mg/dL, diabetes mellitus, and kidney or hepatic chronic diseases. We analyzed the use of the FF in patients with metabolic syndrome. We selected patients with known metabolic syndrome that fulflled the National Cholesterol Education Program Expert Panel on Detection, Evaluation and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) Final Report and excluded patients with triglyceride levels ≥400mg/dL and chronic liver and/or kidney disease. Using direct assays, we measured total cholesterol, high-density lipoprotein cholesterol, triglycerides, and LDL-c. Ten, LDL-c was estimated using the FF and compared with the LDL-c by direct assay. Te sample size was 135 patients. Using the FF, the mean LDL-c value was 124.4 ± 42.1 mg/dL; it was 125.1 ± 38.5 mg/dL by direct assay. Te correlation coefcient between these two methods was 0.89, with statistical signifcance ( value < 0.001). Tere were no signifcant diferences between the patients with triglyceride levels >150 mg/dL ( = 0.618). In conclusion, FF is a good method for estimating LDL-c in patients with metabolic syndrome. 1. Introduction Metabolic syndrome (MS) comprises a group of metabolic abnormalities that are related to high cardiovascular risk, particularly for the development of coronary artery disease (CAD) [1]. MS is highly prevalent in Brazil, afecting approximately 30% of the population. Te prevalence increases in older populations [2]. Te main concern about MS is the development of CAD, which is a highly prevalent condition and a major cause of mortality. In the development of CAD, lipid metabolism, which is the formation of atherosclerotic plaque, plays a major role. Hypercholesterolemia is a lipid abnormality commonly related to atherosclerosis. Nevertheless, LDL-c, which is the major lipoprotein associated with CAD, is not a part of the diagnostic criteria of MS [3–5]. Te physiological levels of LDL-c that are sufcient for lipid metabolism range from 25 to 60 mg/dL, and LDL-c is more atherogenic when it exceeds 100 mg/dL. Terefore, as previously described in the literature, lower levels of LDL-c reduce cardiovascular morbidity and mortality [6–8]. Cardiovascular risk stratifcation defnes the LDL-c value target. Terefore, the LDL-c measurement technique requires standardization and good accuracy [6–10]. Te Friedewald formula (FF) is an estimation of LDL-c level that uses the following levels of total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-c): LDL-c (mg/dL) = TC (mg/dL) − HDL-c (mg/dL) − TG (mg/dL)/5 [6, 11–13]. To be applied in the FF, the measurements of TC, HDL-c, and TG must be in mg/dL; the estimation difers and was not performed for the mmol/L measurements. Te FF became the standard method for LDL- c assessment because it is economical and simpler than direct Hindawi Publishing Corporation Cholesterol Volume 2014, Article ID 261878, 5 pages http://dx.doi.org/10.1155/2014/261878