Tubulointerstitial Nephritis-An Under-Recognized Renal Disease

Background: Tubulointerstitial nephritis (TIN) is an important cause of renal failure. However, the clinical presentation is usually not specific and under-diagnosed. Patients/Methods: A single-center retrospective analysis of renal biopsy results from 346 consecutive patients between 2000 through 2004. Primary target pathogenic process in tubulointerstitial compartment cases was collected. We investigate the TIN prevalence, causative agents and clinical outcome. Results: Primary TIN was identified in 71 (20.5%) biopsies; seven cases were excluded because of incomplete clinical profile. Therefore 64 cases remained for this study. Sixteen patients were ATIN only (Group 1), 26 patients were ATIN superimposed on pre-existing glomerular disease (Group 2) and 22 cases were CTIN (Group 3). Causative agents in ATIN (Group 1 and 2) were: infection in 4, drugs in 11, alternative medicine in 14. Herbal medicines caused 15 of 22 CTIN cases (68.2%). Causes were uncertain in 13 of 42 ATIN and 7 of 22 CTIN cases. Pre-biopsy suspicions were accurate in 27% ATIN with pre-existing glomerulopathy and in 50% ATIN without; it was 91% in CTIN. Renal damage was reversible in 40.5% ATIN and 13.6% CTIN cases. Conclusions: Half of the renal biopsy patients whose clinical diagnosis was not TIN showed it in pathologic findings. TIN incidence is higher than suspected and under-diagnosed in clinical nephrology practice. Drugs and alternative medicines are major causes. Investigating clinical history and emphasize on drug history, and high clinical awareness will improve diagnosis and prevent this devastating renal disorder.