Avaliação da dosagem direta do colesterol-LDL em amostras de sangue de 10.664 pacientes em comparação com o uso da fórmula de Friedewald Comparison of LDL-cholesterol direct measurement with the estimate using the Friedewald formula in a sample of 10,664 patients

OBJETIVO: Avaliar a dosagem direta do colesterol LDL (LDL-C) por um método homogêneo, em comparação com a estimativa pela fórmula de Friedewald, em uma grande população heterogênea. MÉTODOS: As dosagens do colesterol total (ColT) e dos triglicerídeos (Trig) foram realizadas por métodos enzimáticos tradicionais. As dosagens do HDL-C e do LDL-C foram realizadas por métodos diretos, sem precipitação, e a estimativa da fração LDL-C calculada pela fórmula de Friedewald. RESULTADOS: Por análise de regressão linear, os dois métodos apresentaram coeficientes de correlação extremamente significativos (p 201 mg/dL. Este bias positivo também ocorreu com relação a níveis de Trig OBJECTIVE: 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. METHODS: 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. RESULTS: On linear regression analysis, the 2 methods had extremely significant correlation coefficients (P 201 mg/dL. This positive bias also occurred in regard to TG levels < 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 bias of the Friedewald formula became negative. CONCLUSION: The Friedewald formula did not have a homogeneous performance for estimating LDL-C levels in samples with different TG levels as compared with that of the direct method, what could launch doubts on patients classification on the risk of developing coronary artery disease