The cut - off point ≤ 51 years ofage is a significant factor in the predictor of renal function recovery with a sensitivity of 72.7%, a specificity of 63.8%, (p < 0.01, area under curve: AUC = 0.738), the cut - off point of duration of obstruction ≤ 4 weeks is a significant factor in the predictor of renal function recovery with a sensitivity of 72.7%, a specificity of 64.7%, (p < 0.05, AUC = 0.695).