Diagnosing acute tubulointerstitial nephritis: novel biomarkers address an important clinical challenge

Purpose of review Acute tubulointerstitial nephritis (ATIN) is a common cause of acute kidney injury (AKI) that requires diagnosis specific management. Currently available diagnostic tests lack accuracy to distinguish ATIN from various other etiologies of AKI increasing reliance on kidney biopsy for diagnosis, which is associated with procedural risks and possible diagnostic and interventional delays. This review highlights the recent efforts focused on identifying diagnostic biomarkers and addressing this important clinical challenge. Recent findings Numerous research groups have harnessed the increasing knowledge of inflammatory proteins and cytokines upregulated in ATIN to identify reliable diagnostic biomarkers, these include C-X-C motif ligand 9, tumor necrosis factor alpha, interleukin-9, urinary regulated on activation normal T cell expressed and secreted, among others. Parallel work has also focused on identifying imaging and pathological markers associated with ATIN as well as a diagnostic model that combines currently available clinical tests for ATIN diagnosis. Summary Biomarkers have shown promise as diagnostic tools for ATIN; however, most studies have limitations such as small sample sizes, and lack of external validation. Future progress will rely on larger collaborative efforts to identify the most accurate biomarker or combination of biomarkers for integration into diagnostic workup of ATIN.