Comparación de los métodos de Friedewald y Vujovic con la concentración de LDL calculada en un autoanalizador bioquímico / Comparison of the Friedewald and Vujovic methods with the calculated LDL concentration in a biochemical auto-analyzer

Objective To compare the concentration of Low-Density Lipoprotein (LDL-c) obtained using the Friedewald formula with those obtained directly with the RAYTO CHEMRAY 120 autoanalyzer. Methods Cross-sectional study. We evaluated outpatients with a medical request for a lipid profile study (total cholesterol, triglycerides, LDL, and HDL). The analyses were carried out in a RAYTO CHEMRAY 120 autoanalyzer under the principle of spectrophotometry. We obtained LDL-c using the Friedewald and Vujovic formulas. Results We evaluated 199 individuals whose direct LDL concentration averages were measured by the RAYTO CHEMRAY 120 equipment. Those calculated by the Friedewald and Vujovic formulas were 129.97 ± 32.66, 119.28 ± 30.44, and 127.01 ± 32.01, respectively, and in all cases, significant differences (P < 0.001) were observed with the RAYTO analyzer. In both cases a low positive bias was found with the RAYTO analyzer.. The Passing-Bablok and Deming's regressions showed a linear correlation between both methods (Friedewald and Vujovic) with the LDL values obtained with the Rayto autoanalyzer. Conclusions Our study found that the Friedewald and Vujovic methods are good predictors of LDL cholesterol levels and have a low level of bias. Therefore, they could be used as potential predictors.

Objetivo Comparar las concentraciones de Lipoproteínas de Baja Densidad (LDL-c) obtenidas mediante la fórmula de Friedewald con las obtenidas directamente con el autoanalizador RAYTO CHEMRAY 120. Métodos Estudio transversal. Se evaluaron pacientes ambulatorios con solicitud médica de perfil lipídico (colesterol total, triglicéridos, LDL y HDL). Los análisis se realizaron con un autoanalizador RAYTO CHEMRAY 120 bajo el principio de espectrofotometría. Obtuvimos el LDL-c usando las fórmulas de Friedewald y Vujovic. Resultados Se evaluaron 199 individuos cuyos promedios directos de concentración de LDL fueron medidos con el equipo RAYTO CHEMRAY 120. Las concentraciones calculadas por las fórmulas de Friedewald y Vujovic fueron de 129,97 ± 32,66, 119,28 ± 30,44, y de 127,01 ± 32,01, respectivamente, y en todos los casos se observaron diferencias significativas (P < 0,001) con el analizador RAYTO. En ambos casos se encontró un sesgo positivo bajo en el analizador RAYTO. Las regresiones de Passing-Bablok y Deming mostraron una correlación lineal entre ambos métodos (Friedewald y Vujovic) con los valores de LDL obtenidos con el autoanalizador Rayto. Conclusión Nuestro estudio encontro que los métodos de Friedewald y Vujovic son buenos predictores de los niveles de colesterol LDL y presentan un nivel de sesgo bajo. Por lo que podrían usarse como potenciales predictores.

Comparison of the Friedewald and Vujovic methods with the calculated LDL concentration in a biochemical auto-analyzer.

Objective: To compare the concentration of Low-Density Lipoprotein (LDL-c) obtained using the Friedewald formula with those obtained directly with the RAYTO CHEMRAY 120 autoanalyzer. Methods: Cross-sectional study. We evaluated outpatients with a medical request for a lipid profile study (total cholesterol, triglycerides, LDL, and HDL). The analyses were carried out in a RAYTO CHEMRAY 120 autoanalyzer under the principle of spectrophotometry. We obtained LDL-c using the Friedewald and Vujovic formulas. Results: We evaluated 199 individuals whose direct LDL concentration averages were measured by the RAYTO CHEMRAY 120 equipment. Those calculated by the Friedewald and Vujovic formulas were 129.97 ± 32.66, 119.28 ± 30.44, and 127.01 ± 32.01, respectively, and in all cases, significant differences (P < 0.001) were observed with the RAYTO analyzer. In both cases a low positive bias was found with the RAYTO analyzer.. The Passing-Bablok and Deming's regressions showed a linear correlation between both methods (Friedewald and Vujovic) with the LDL values obtained with the Rayto autoanalyzer. Conclusions: Our study found that the Friedewald and Vujovic methods are good predictors of LDL cholesterol levels and have a low level of bias. Therefore, they could be used as potential predictors.

Objetivo: Comparar las concentraciones de Lipoproteínas de Baja Densidad (LDL-c) obtenidas mediante la fórmula de Friedewald con las obtenidas directamente con el autoanalizador RAYTO CHEMRAY 120. Métodos: Estudio transversal. Se evaluaron pacientes ambulatorios con solicitud médica de perfil lipídico (colesterol total, triglicéridos, LDL y HDL). Los análisis se realizaron con un autoanalizador RAYTO CHEMRAY 120 bajo el principio de espectrofotometría. Obtuvimos el LDL-c usando las fórmulas de Friedewald y Vujovic. Resultados: Se evaluaron 199 individuos cuyos promedios directos de concentración de LDL fueron medidos con el equipo RAYTO CHEMRAY 120. Las concentraciones calculadas por las fórmulas de Friedewald y Vujovic fueron de 129,97 ± 32,66, 119,28 ± 30,44, y de 127,01 ± 32,01, respectivamente, y en todos los casos se observaron diferencias significativas (P < 0,001) con el analizador RAYTO. En ambos casos se encontró un sesgo positivo bajo en el analizador RAYTO. Las regresiones de Passing-Bablok y Deming mostraron una correlación lineal entre ambos métodos (Friedewald y Vujovic) con los valores de LDL obtenidos con el autoanalizador Rayto. Conclusión: Nuestro estudio encontro que los métodos de Friedewald y Vujovic son buenos predictores de los niveles de colesterol LDL y presentan un nivel de sesgo bajo. Por lo que podrían usarse como potenciales predictores.

Leadcare® II Comparison with Graphite Furnace Atomic Absorption Spectrophotometry for Blood Lead Measurement in Peruvian Highlands.

Peru is one of the countries with the highest lead contamination in the world. Biological monitoring has limitations due to the shortage of laboratories with validated methodologies for the measurement of blood lead, and it is necessary to use alternative methods for its measurement in high-altitude cities. We aimed to compare the blood lead levels (BLL) measured by the LeadCare II (LC) method and Graphite Furnace Atomic Absorption Spectrometry (GF-AAS). We measured the BLL of 108 children from the city of La Oroya. The mean and median BLL for GF-AAS were 10.77 ± 4.18 and 10.44 µg/dL, respectively; for the LC method, the mean was 11.71 ± 4.28 and the median was 11.60 µg/dL. We found a positive linear correlation (Rho = 0.923) between both methods. Notwithstanding, the Wilcoxon test suggests a significant difference between both methods (ρ = 0.000). In addition, the Bland-Altman analysis indicates that there is a positive bias (0.94) in the LC method, and this method tends to overestimate the BLL. Likewise, we performed a generalized linear model to evaluate the influence of age and hemoglobin on BLL. We found that age and hemoglobin had a significant influence on BLL measured by the LC method. Finally, we used two non-parametric linear regression methods (Deming and Passing-Bablok regression) to compare the LC method with the GF-AAS. We found that these methods differ by at least a constant amount, and there would be a proportional difference between both. Although in general there is a positive linear correlation, the results of both methods differ significantly. Therefore, its use in cities located at high altitudes (higher than 2440 m.a.s.l.) would not be recommended.