Oxidized LDL but not total LDL is associated with HbA1c in individuals without diabetes.

OBJECTIVE: This study investigates the association between HbA1c, LDL and oxi-LDL in individuals without diabetes (DM). METHODS: One hundred and ninety-six individuals, without DM, were enrolled and divided into three groups according to HbA1c and fasting plasma glucose values. HbA1c, oxi-LDL, LDL, and other biochemical measurements of lipid profile were also carried out. RESULTS: oxi-LDL levels showed significant differences among all groups and group 3 presented higher values [34U/L (27-46); 44U/L (37-70); and 86U/L (49-136); p<0.001; for groups 1, 2 and 3, respectively]. There was also a significant difference in oxi-LDL/HDL and oxi-LDL/LDL ratios among all groups (p<0.001). There was no significant difference in total cholesterol (TC), triglycerides and LDL values among groups. HbA1c showed moderate positive associations with oxi-LDL (r=0.431; p<0.001), oxi-LDL/HDL ratio (r=0.423, p<0.001), and oxi-LDL/LDL ratio (r=0.359, p<0.001). There were lower associations between HbA1c and TC (r=0.142; p=0.048), triglycerides (r=0.155; p=0.030), LDL (r=0.148; p=0.039), non-HDL (r=0.192; p=0.007) and Apo B (r=0.171, p<0.001). The positive associations between HbA1c and oxi-LDL, oxi-LDL/HDL and oxi-LDL/LDL ratios remained significant even after adjustment by multiple linear regression analysis for the variables alcohol consumption, use of medicine, BMI, and age. CONCLUSIONS: oxi-LDL levels are significantly associated with HbA1c in non-diabetic individuals. However, the levels of traditional atherogenic lipids only showed a weak association with HbA1c levels. Those at high risk of developing DM or cardiovascular disease have higher levels of oxi-LDL. These data favor to the use of HbA1c as a biomarker to identify individuals at risk of developing complications even in non-diabetic glycemic levels.

Efeito da calibração da creatinina sobre a estimativa da taxa de filtração glomerular pela equação MDRD / Effect of creatinine assay calibration on glomerular filtration rate prediction by MDRD equation

Introdução: A avaliação da função renal deve ser realizada através da estimativa da taxa de filtração glomerular (TFG) com a equação do estudo Modification of Diet in Renal Disease (MDRD), a qual inclui a idade, gênero, etnia e creatinina. No entanto, a medida da creatinina requer rastreabilidade com método padrão (equiparação) para sua calibração. Objetivo: Verificar o impacto da calibração da creatinina na TFG calculada pela fórmula do MDRD. Métodos: Foram analisadas 140 amostras de soro com creatinina <2,0 mg/dl pela reação de Jaffé com Creatinina Modular P (Roche ®; método A; calibrado) e pela Creatinina Advia 1650 (Bayer ®; método B; não calibrado). Os resultados obtidos foram comparados entre si e alinhados por fórmula de conversão. A TFG foi estimada através da fórmula do MDRD. Resultados: O método B teve resultados mais altos que o método A (1,03 ± 0,29 vs. 0,86 ± 0,32 mg/dl, P<0,001). Esta diferença diminuiu quando os resultados do método B foram alinhados ao método A através da equação y=1,07x -0,249, sendo os valores do método alinhado por regressão de 0,9 ± 0,31 mg/dl. O método não calibrado identificou 10% mais de casos de doença renal renal crônica (falso positivos). Essa discordância desaparece após o alinhamento. Conclusão: A calibração dos métodos de creatinina tem um impacto importante nos resultados finais de creatinina e TFG. O alinhamento de resultados não padronizados através de fórmulas de conversão pode ser uma alternativa para harmonizar os resultados de creatinina sérica enquanto programas internacionais de padronização não estiverem ainda totalmente implantados.

Background: The evaluation of renal function should be performed with glomerular filtration rate (GFR) estimation employing the Modification of Diet in Renal Disease (MDRD) study equation, which includes age, gender, ethnicity and serum creatinine. However, creatinine methods require traceability with standardized methods. Objective: To analyse the impact of creatinine calibration on MDRD calculated GFR. Methods: 140 samples of plasma with creatinine values <2.0 mg/dl were analysed by Jaffé’s reaction with Creatinina Modular P (Roche ®; method A; reference) and Creatinina Advia 1650 (Bayer ®; method B; nonstandardized). The results with the different methods were compared and aligned with standardized method through a conversion formula. MDRD GFR was estimated. Results: Values were higher for method B (1.03 ± 0.29 vs. 0.86 ± 0.32 mg/dl, P<0.001). This difference declined when methods were aligned with the equation y=1.07x - 0.249, and the aligned values were 0.9 ± 0.31 mg/dl. Non-traceable creatinine methods misclassificaed chronic kidney disease in 10% more (false positive). This disagreement disappeared after the regression alignment. Conclusion: Creatinine method calibration has a large impact over the final results of serum creatinine and GFR. The alignment of the non-standardized results through conversion formulas is a reasonable alternative to harmonize serum creatinine results while waiting for the full implementation of international standardization programs.