Aim: Urinary cytokine excretion may reflect histological changes in immunoglobulin A nephropathy (IgAN), and their measurement can give information about disease outcome.
Methods: Thirty-three IgAN patients were prospectively followed for 5.6 +/- 3.1 years. Urinary levels of monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-6 and epidermal growth factor (EGF) were measured at diagnosis and repeated 1 year later for IL-6 and EGF.
Results: Urinary MCP-1 and IL-6 levels were increased significantly, while EGF excretion reduced in IgAN patients, compared to controls. IL-6 urinary levels showed significant positive correlation with chronic histological lesions. Patients were classified into five groups, according to the Haas classification system. MCP-1 and IL-6 urinary levels were increased, whereas EGF levels were reduced in the progression of staging. EGF urinary excretion was a strong predictor factor of disease outcome, significantly correlated with creatinine clearance at time of diagnosis (r = 0.5, P = 0.005), and at the end of follow up (r = 0.6, P = 0.001). Urinary EGF levels measured a year later could predict long-term outcome better, and a cut of 0.05 pg/mg urine creatinine levels could distinguish between progressors and non-progressors.
Conclusion: Urinary MCP-1, IL-6 and EGF levels may represent histology in IgAN. EGF excretion can be a predictive marker and its serial measurements may give information about disease outcome and the effect of treatment.