Abstract: Objectives To investigate whether urinary Tamm- Horsfall protein (uTHP) level combined with urinary complement factor H (uCFH) level can correlate with IgA nephropathy histology Haas classification and renal outcome. Methods A total of 351 IgA nephropathy patients followed up from Sep. 2003 to Sep. 2014 were enrolled in this study. Histological changes were evaluated by using the Haas classification of IgA nephropathy. Enzyme linked immunosorbent assay (ELISA) was used to measure uTHP and uCFH levels at the renal biopsy day. Composite endpoint of renal outcome was defined as ①end-stage renal disease (ESRD), ②≥ 50% decline of estimated glomerular filtration rate (eGFR), and ③doubling of plasma creatinine level. Results In this cohort, patients with lower uTHP level and higher uCFH level had more proteinuria (χ²=37.899, P＜0.001), lower blood albumin (χ²=37.487, P＜0.001), lower eGFR(F=16.333, P＜0.001), severer histological lesion (χ²=52.304, P＜0.001) and worse renal outcome (χ2=35.678, P＜0.001). Kaplan-Meier curve analysis indicated that lower uTHP level with higher uCFH level predicted the worse renal outcome during follow-up (Log Rank test, χ²=31.938, P＜0.001). Conclusions uTHP level combined with uCFH level can predict renal outcome in IgA nephropathy patients. Patients with lower uTHP and higher uCFH will have severer morphological lesions (Haas classification) and worse renal outcome.

Key words: Tamm-Horsdall Protein, Complement factor H, IgA nephropathy, Haas classification.