Acute interstitial nephritis (AIN) is a potentially reversible cause of acute kidney injury, yet diagnosis and follow-up remain challenging in routine practice.1-3 Kidney biopsy is the reference standard but is invasive and not always feasible.4 Urinary chemokines such as CXCL9 and CXCL10 have emerged as promising biomarkers of AIN,5-7 but their role in daily practice, particularly for longitudinal disease monitoring, remains incompletely defined.