Kidney injury molecule-1 levels are associated with therapeutic outcomes and renal tubulointerstitial injury severity in idiopathic membranous nephropathy.

Kidney injury molecule-1 (KIM-1) has an important role in chronic kidney disease development. The present study aimed to retrospectively analyze patients with idiopathic membranous nephrology (IMN) with different therapeutic outcomes to investigate the association between KIM-1 levels and therapeutic outcomes. A total of 51 patients with IMN and 20 healthy controls were included. Patients were classified into three groups: Spontaneous remission, remission with immunosuppressive therapy (IST) and nonremission with IST. Clinical and biochemical variables were collected. Urinary KIM-1 levels were measured by ELISA and renal KIM-1 expression was evaluated by immunohistochemistry. Patients with IMN were characterized as having elevated urinary and renal KIM-1 levels compared with those in the controls. Significantly increased urinary and renal KIM-1 levels were observed in the nonremission with IST group compared with those in the spontaneous remission group, and the same trend was observed for the plasma anti-podocyte antigen phospholipase A2 receptor antibody levels. Patients with more severe tubular injury (T2 index) presented with significantly higher urinary and renal KIM-1 levels than those with the T0 index. Urinary and renal KIM-1 levels were positively correlated with blood urea nitrogen, serum creatinine, serum cystatin-C, urinary albumin/creatinine ratio, urinary β2-microglobulin and the renal interstitial fibrosis index, and they were negatively correlated with serum albumin. Furthermore, urinary KIM-1 levels were positively correlated with the renal KIM-1 levels. In conclusion, the measurement of urinary and renal KIM-1 levels may be helpful in guiding medication selection and predicting therapeutic outcomes for patients with IMN.