Effect of Glucocorticoid Use in Patients With Biopsy-Proven Acute Interstitial Nephritis: Insights From a Colombian Cohort.

Introduction: Acute interstitial nephritis (AIN) is a major cause of acute kidney injury, commonly triggered by medications or infections. Although glucocorticoid (GC) therapy is recommended for patients who do not improve after removing the suspected cause, the evidence supporting its use remains limited. Materials and Methods: This retrospective cohort study was conducted at the Pathology Unit of the University of Antioquia-San Vicente Fundación Hospital in Medellín, Colombia, reviewing patients aged 14 and older with biopsy-proven AIN over an 11-year period. Two groups were formed based on whether or not they received GC treatment. Key outcomes included changes in delta creatinine (serum creatinine change from peak to 6-month follow-up) and the need for permanent kidney replacement therapy. Linear regression analyses assessed factors influencing delta creatinine at 6 months, adjusting for age, clinical severity, time to GC initiation, and histological findings. Results: Of 139 eligible patients, 101 received GC therapy. The GC-treated group showed a significantly greater reduction in delta creatinine compared to the nontreated group (-2.3 mg/dL; 95% CI, -3.6 to -1.1, p < 0.001). Multivariate analysis identified GC therapy as an independent predictor of improved kidney function (delta creatinine reduction: -1.47 mg/dL; 95% CI, -2.68 to -0.27, p=0.017), particularly when initiated within 7 days of diagnosis. The GC-treated group also had a lower incidence of permanent dialysis dependence (54% at admission vs. 11% at 6 months). Adverse events occurred in 20.1% of the cohort, with a higher frequency in the GC group (p=0.076). Conclusion: GC therapy may improve kidney outcomes in patients with biopsy-proven AIN, especially when initiated early. These results support the need for prospective studies to further evaluate its efficacy in AIN management.