Clinical Profile and Risk Factors of Tubulointerstitial Nephritis: A Retrospective Study

Background: Tubulointerstitial nephritis—including chronic tubulointerstitial disease (CTID), acute interstitial nephritis (AIN), and granulomatous interstitial nephritis (GIN)—are important causes of kidney disease. We examined the clinical profile of affected patients at our center. Methods: Medical records of patients diagnosed with CTID, AIN, and GIN on kidney biopsy in the nephrology department (2013–2023) were reviewed. Approved by the institute ethics committee. Results: 121 patients were included: 85 with CTID, 21 with AIN, and 15 with GIN. Median ages (IQR) were 35 (27–49), 39 (28–47), and 50 (36–55) years, respectively. Males accounted for 67.1% (CTID), 38.1% (AIN), and 46.7% (GIN). Median eGFR (IQR) at biopsy was 29.1 (16.9–46.2), 28.0 (12.2–37.5), and 26.7 (13.6–36.3) mL/min/1.73m^2, with urine protein excretion of 1.1 (0.4–2.0), 0.8 (0.4–2.0), and 0.8 (0.4–2.4) g/day in CTID, AIN, and GIN, respectively. Hematuria (≥5 RBCs/hpf) was reported in 28.2% (CTID), 47.6% (AIN), and 13.3% (GIN); pyuria (≥5 WBCs/hpf) in 41.2%, 13.3%, and 23.8%, respectively. 47 (55.3%) CTID cases had no identifiable cause while risk factors included were NSAIDs (n=15), CAM (n=11), antibiotics (n=8), chemotherapy (n=6), supplements (n=2), Sjögren’s (n=3), and IgG4-related disease (n=2). GIN was linked to sarcoidosis (n=3), TB (n=1), UTI (n=1), NSAIDs (n=2), and CAM (n=2). NSAIDs (n=6), CAM (n=2), Sjögren’s (n=3), and chemotherapy (n=2) were noted in AIN. Some had multiple risk factors. Conclusion: Tubulointerstitial diseases often manifest with kidney impairment and sub-nephrotic proteinuria. While drug exposures—both conventional and alternative—are frequently implicated, the underlying cause remains unidentified in many cases. - Variable CTID (n=85)^1 AIN (n=21)^1 Granulomatous Nephritis (n=15)^1 Age (years) 35 (25-49) 39.0 (28.0-47) 50 (36-55) Sex (Male) 57 (67.1%) 8 (38.1%) 7 (46.7%) Diabetes 6 (7.1%) 4 (19.0%) 1 (6.7%) Hypertension 34 (40.0%) 4 (19.0%) 5 (33.3%) Serum Creatinine (mg/dl) 2.6 (1.8-3.8) 2.7 (1.8-5.0) 2.7 (1.8-4.5) eGFR (ml/min/1.73m^2) 29.1 (16.9-46.2) 28.0 (12.2-37.5) 26.7 (13.6-36.3) Serum Albumin (g/dl) 4.1 (3.6-4.6) 3.8 (3.1-4.3) 4.1 (3.5-4.4) Urine Protein (g/day) 1.1 (0.4-2) 0.8 (0.4-2.0) 0.8 (0.4-2.4) Hematuria 24 (28.2%) 10 (47.6%) 2 (13.3%) Pyuria 35 (41.2%) 2 (13.3%) 5 (23.8%) n^1 (%); Median (IQR)