Clinical Tools for the Diagnosis of Acute Tubulointerstitial Disease.

Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury (AKI), occurring in up to a quarter of kidney biopsies performed for AKI. ATIN can lead to chronic kidney disease if not promptly diagnosed and managed. The most common cause is drugs, with antibiotics being the most commonly reported cause. Widespread use of proton pump inhibitors and increasing use of immuno-oncotherapy, such as immune checkpoint inhibitors, are contributing to increased incidence of ATIN. However, there are diagnostic challenges. The time of onset of AKI in ATIN is variable, and diagnosis is often delayed due to a lack of specific symptoms or clinical findings. No standard diagnostic criteria exist even for histological diagnosis despite kidney biopsy being the gold standard. Additionally, there are no available tools to distinguish between different causes of ATIN, particularly when multiple etiologies are suspected, and to identify those who will benefit from treatment at diagnosis. Particularly with oncotherapy-associated AKI, where discontinuing the drug portends detrimental effects on the patient, diagnostic tools with high accuracy for distinguishing ATIN from other types of AKI are paramount. Herein, we discuss the current evidence on the diagnosis of ATIN with a focus on available clinical, laboratory, and imaging findings.