Abstract:

Objective　To research the cut-off value of microalbuminuria with urine albumin to creatinine ratio（ACR） and urinary albumin（U-Alb） concentration of first morning urine and random urine samples among type 2 diabetes mellitus（T2DM）， in order to detect early diabetic kidney disease（DKD）. Methods　A total of 169 T2DM patients and 40 healthy subjects（healthy control group） were enrolled. Their 24 h urine， first morning urine and random urine samples were collected. The 24 h urinary albumin excretion （UAE） was referred as the gold standard of early DKD， and the detection effectiveness of early DKD was evaluated when applied ACR and U-Alb concentration from first morning urine and random urine samples. According to receiver operating characteristic （ROC） curve analysis， the value with the maximum Youden index was the appropriate microalbuminuria cut-off value of ACR and U-Alb concentration from first morning urine and random urine samples for detecting early DKD. Results　The coincidence of ACR and U-Alb concentration with 24 h UAE from first morning urine samples were 43% and 37%， and those of ACR and U-Alb concentration from random urine samples were 48% and 41%， which were all significantly different with 24 h UAE（P＜0.001）. In healthy control group， the microalbuminuria judgment was totally normal and consistent with 24 h UAE. ROC curve analysis indicated that the cut-off values of ACR from first morning urine samples were male 16 mg/g and female 23 mg/g （Youden indices 0.7 and 0.67， negative predictive values 97% and 100%， and positive predictive values 72% and 65%， respestively）， and those of ACR from random urine samples were male 17 mg/g and female 28 mg/g（Youden indices 0.68 and 0.67， negative predictive values 90% and 90% and positive predictive values 61% and 82%， respectively）. Those of U-Alb concentration from first morning urine samples were male 16 mg/L and female 15 mg/L（Youden indices 0.57 and 0.59， negative predictive values 84% and 87%， and positive predictive values 90% and 73%， respectively）， and those of U-Alb concentration from random urine samples male 17 mg/L and female 14 mg/L（Youden indices 0.56 and 0.53， negative predictive values 73% and 81%， and positive predictive values 85% and 71%， respectively）. The maximum Youden index of ACR was >0.6 and better than the Youden index of U-Alb concentration. Conclusions　The missing diagnosis rate is high when detecting early DKD among T2DM patients with current clinical microalbuminuria cut-off value from first morning urine and random urine samples. The cut-off values of ACR and U-Alb concentration from first morning urine and random samples should be established in order to facilitate the early prevention and treatment of DKD.

Key words: Albumin to creatinine ratio, Albumin, Urine, Cut-off value, Type 2 diabetes mellitus, Diabetic kidney disease