High serum level of methylglyoxal-derived AGE, Nδ-(5-hydro-5-methyl-4-imidazolone-2-yl)-ornithine, independently relates to renal dysfunction

The dicarbonyl methylglyoxal reacts primarily with arginine residues to form advanced glycation end products, including N delta-(5-hydro-5-methyl-4 -imidazolone-2-yl)-ornithine (MG-H1), which are risk factors for not only diabetic complications but also lifestyle-related disease including renal dysfunction. However, the data on serum level and clinical significance of this substance in chronic kidney disease are limited. Serum levels of MG-H1 and N epsilon-(carboxymethyl) lysine (CML) in 50 patients with renal dysfunction were measured by liquid chromatography/triple-quadruple mass spectrometry. The median serum MG-H1 levels in patients with estimated glomerular filtration rate (eGFR) of ae30, 15-30, and < 15 ml/min/1.73 m(2) was 4.16, 12.58, and 14.66 mmol/mol Lys, respectively (p > 0.05). On the other hand, MG-H1 levels in patients with HbA1c of < 6 and ae6 % was 12.85 and 10.45 mmol/mol Lys, respectively, the difference between which is not significant. In logistic regression analysis, decreased renal function (eGFR < 15 ml/min/1.73 m(2)) significantly associated with high serum levels of MG-H1 [odds ratio: 9.39 (95 % confidence interval 1.528-57.76), p = 0.015; Spearman rank correlation: MG-H1 vs. eGFR, r = -0.691, p < 0.01]. In contrast, the serum level of CML did not correlate with eGFR, but correlated with systolic blood pressure [odds ratio 16.17 (95 % confidence interval 1.973-132.5), p = 0.010; Spearman rank correlation coefficient: CML vs. eGFR, r = 0.454, p < 0.01]. These results showed that the serum concentration of MG-H1 was strongly related to renal function rather than to DM.