Urinary transferrin and proinflammatory markers predict the earliest diabetic nephropathy onset.

Aim: This study aimed to determine the earliest markers of diabetic nephropathy (DN) onset with discriminative potentials from controlled diabetes (CD).

Methods: Sixty male Wistar rats were allocated into three groups (20/group), the two diabetic groups CD and DN received 45 and 65 mg/kg STZ in 0.1 mole/L citrate buffer, respectively, while the control group received only the vehicle. Serum/urinary levels of glomerular, tubular, oxidative and proinflammatory markers were weekly monitored.

Results: Each diabetic group showed a different pattern of inflammatory, oxidative and signs of nephropathy along the study period, but none had a discriminative power until the fourth week. At this time point, levels of urinary transferrin, serum/urinary IL-6 and TNF-α as well as urinary IL-18 were significantly higher in DN group compared to CD ( = 0.0217, <0.0001, 0.0005, 0.0004, 0.0006, 0.0019, respectively). Predictive thresholds of these markers were calculated by receiver operating characteristic (ROC) curve that showed area under curve (AUC) of 0.9375 for transferrin with cut-off value of 35.2 mg/dL and 1.000 for serum/urinary IL-6 and TNF-α and urinary IL-18 with cut-of values 224.1, 82.11, 6.596, 125.9 and 21.86 pg/mL, respectively.

Conclusion: Urinary transferrin and the inflammatory endpoints proposed in this study might represent promising biomarkers for the early DN onset.