Acute tubulointerstitial nephritis in adults: A retrospective case series from a nephrology center in Tunisia and literature review

Abstract

Background Acute interstitial nephritis (AIN) is a leading cause of acute kidney injury that shows variability in incidence and etiology based on geography. In recent years, there have been significant changes in its diagnostic and therapeutic approach. The study aimed to offer an understanding of 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 a 16-year period. The collected data consisted of demographic information, initial clinical and biochemical findings, renal biopsy results, treatment approaches, and follow-up details. Results We gathered 36 confirmed cases of biopsy proven AIN with an annual incidence rate of 2.5 cases. The average age of the patients was 50.58 years, with a male-to-female ratio of 0.71. The predominant clinical signs were fatigue (58%) and fever (22%). The mean levels of creatinine and eosinophils were 691.58 µmol/l and 481.66 10^9/L, respectively. On kidney biopsy, 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 were responsible for 16.66% and 11.11% of cases, respectively. We have identified two exceptional causes of AIN, one associated with treatment with Rituximab and the other with a triple parasitic infection. AIN associated with malignancies were seen in 2.77% of cases, with some cases (25%) lacking an identifiable cause. Corticosteroid treatment was recommended for 93.33% of cases presenting with immune allergic AIN and those associated with systemic diseases. The median follow-up duration was 2.2 years. Seven patients required hemodialysis during the acute phase, and 71.42% showed recovery in renal function. The presence of interstitial fibrosis correlated with the progression to chronic kidney disease. Conclusion Acute Interstitial Nephritis (AIN) is a leading cause of acute kidney injury that can progress to chronicity. Interstitial fibrosis is associated with the progression to chronic kidney failure. The primary etiology is drug intake, and some causes are yet to be identified.