Diagnostic value of serum miR-21 for diabetic nephropathy

AIM:To evaluate the diagnostic value of serum miR-21 as a molecular biomarker in the patients with diabetic nephropathy (DN). METHODS:Twenty-five patients with DN, 50 patients with type II diabetes ［divided into DMA group and DMB group base on urinary microalbumin (UmAlb), 25 in each group］, 25 patients with diabetic nephropathy-induced uremia (UM) and 25 normal controls (NC) were included in the study. Total RNA was extracted from the serum samples for determining the miR-21 level using real-time PCR. The relationship between miR-21 level and clinical parameters of the patients with diabetic nephropathy was analyzed. RESULTS:The relative expression level of serum miR-21 was significantly lower in DN group than that in DMA group, DMB group and NC group, and was significantly higher than that in UM group (all P<001). The serum miR-21 level showed significant negative correlation with cystatin C, UmAlb, UmAlb/urinary creatinine in DN patients (P<0.01，P<0.05，P<0.05). For discriminating the DN patients from NC, DMA, DMB, DMA＋NC, DMB＋NC and DMA＋DMB, the areas under the receiver operating characteristic curve (AUC-ROC) for serum miR-21 were 0848 (95% CI: 0737~0959), 0896 (95% CI: 0812~0980), 0782 (95% CI: 0641~0922), 0838 (95% CI: 0743~0933), 0796 (95% CI: 0675~0917) and 0808 (95% CI: 0704~0911), and the sensitivity and specificity were 800% and 720%, 720% and 880%, 720% and 840%, 760% and 770%, 760% and 820%, 700% and 860%, respectively. For discriminating the DN patients from DMA＋DMB＋NC, the AUC-ROC was 0845 (95% CI: 0752~0939), and the sensitivity and specificity were 760% and 773%， respectively. CONCLUSION: Serum miR-21 can serve as a molecular diagnostic marker for diagnosis of diabetic nephropathy.