Acute interstitial nephritis in adults: A retrospective case series from a nephrology center in Tunisia

Introduction-Aim: Acute interstitial nephritis (AIN) shows variability in incidence and etiology based on geography.  The study aimed to understand the characteristics and root causes of AIN, its diagnosis methods, treatment strategies, and results within a Tunisian population. Method: We retrospectively gathered data on biopsy-proven AIN from a Nephrology center over 16 years.  Results: We gathered 36 confirmed cases of biopsy-proven AIN. The average age of the patients was 50.58 years. The predominant clinical signs were fatigue (58%) and fever (22%). The mean level of creatinine was 691.58 µmol/l. Interstitial infiltrate was significant in 52.77% of cases, with eosinophils present in only 5.55% of cases and fibrosis noted in 27.77% of cases. Drug-related causes accounted for 46.66% of AIN cases, while infections and systemic diseases accounted for 16.66% and 11.11%, respectively. We have identified two exceptional causes of AIN, one associated with treatment with Rituximab and the other with a triple parasitic infection. Some cases (25%) lacked an identifiable cause. Corticosteroid treatment was recommended for 93.33% of cases. The median follow-up duration was 2.2 years. Seven patients required hemodialysis, and 71.42% recovered renal function. The presence of interstitial fibrosis correlated with the progression to chronic kidney disease. Conclusion: AIN is a leading cause of acute kidney injury that can progress to chronicity. Interstitial fibrosis is associated with the progression of chronic kidney disease. The primary etiology is drug intake, and some causes are yet to be identified.