Introduction:
Acute interstitial nephritis (AIN) is one of the frequent causes of acute kidney injury (AKI). In the previous studies from India, infections and drugs were the most common causes of AIN. This study aims to examine the etiology, clinicopathological profile, and outcomes of patients presenting with biopsy-proven AIN at our institution.
Methods:
This retrospective record-based study included all patients with biopsy-proven acute interstitial nephritis from 2014 to 2024. Complete recovery was defined as those with serum creatinine within 15 % of the baseline at three months if available or eGFR > 60ml/min at three months. Patients with dialysis requiring Renal failure at three months and those with eGFR < 60ml/min or if serum creatinine above 15% of baseline at three months were considered as progression to chronic kidney disease(CKD). The primary outcome was identifying the etiological factors of AIN and the clinical presentation. The secondary outcomes assessed the proportion of patients' complete recovery, progression to CKD or dialysis requiring renal failure at three months, and the relationship between histopathological features and treatment outcomes at three months. The data was collected using a data collection proforma and analyzed using SPSS v21.
Results:
A total of 55 cases of biopsy-proven AIN were identified, out of which 35% were women. The mean age was 43 years(12-68). At presentation,16% of patients had fever, and 5.3% had arthralgia. About 26% had oliguria, 9% had hematuria, and 12.3% had nephrotic range proteinuria. Eleven patients(19.3 %) had dialysis requiring renal failure at presentation. The median eGFR at presentation was 18.9 ml/min/m2 (10.2- 41.3) Only 11(19.3%) had peripheral eosinophilia, while 10 (17.5%) had low platelet count. About 62% of patients had albuminuria. Fifteen patients(30%) and 27(47%) had RBCs and WBCs in urine, respectively. Around 10.5% had eosinophils in their urine. Urine culture was positive in 6( 10.5%) patients. Exposure to NSAIDs was 10.5%, antibiotics were 14%, and native medications were 5.3%. Around 12.3% had snake bites, 12 % had wasp or bee stings, and 42% had unidentified etiology. Two patients had acute pyelonephritis with interstitial nephritis. In kidney biopsy, 24% of patients had eosinophil predominance, and 56% had only lymphocytic infiltration in the interstitium. Median eGFR at 3 months was 30.8ml/min/m2.(13-65ml/min/m2). Forty-one patients(74.5%) had progressed to CKD at 3 months follow-up. There was complete recovery in 14 patients (24.5%). Histopathological features of tubular atrophy and interstitial fibrosis were associated with progression to CKD.
Conclusions:
Unlike data from previous studies in India, our center had a significant proportion (50%) of AIN due to drugs, insect bites, or snake bites. Progression to CKD was noted in 75% of patients at 3 months follow up.
I have no potential conflict of interest to disclose.
I did not use generative AI and AI-assisted technologies in the writing process.