A new study published inBMC Nephrologyin 2025, reports that carbonic anhydrase 3 detected in urine may serve as a useful biomarker for monitoring renal injury in patients with atherosclerotic renal artery stenosis. The authors explain that this vascular condition reduces blood supply to the kidneys, leading to progressive functional decline, yet current diagnostic methods rely heavily on imaging and invasive procedures. Identifying a protein such as carbonic anhydrase 3 in urine, which reflects interstitial damage, could provide a safe and non-invasive alternative to monitor disease progression and treatment response. The researchers applied proteomic screening to identify candidate proteins and then validated carbonic anhydrase 3 as the most promising urinary signal. They found that levels of this protein, normalized to creatinine, were consistently elevated in patients with renal artery stenosis compared to disease and healthy controls. Because urine collection is simple, inexpensive, and non-invasive, this approach could potentially allow earlier identification of renal damage and closer tracking of patient outcomes. However, the authors stress that their findings need confirmation through larger trials and more detailed mechanistic work to establish specificity and clinical reliability. This work adds to the growing field of urinary proteomics, where molecular signals are being explored as tools for early detection of cardiovascular and renal disease. By pointing to carbonic anhydrase 3 as a marker of ischemic kidney injury, the study opens new possibilities for patient-friendly diagnostics. Still, the translation of these findings into practice will depend on whether future studies can show that urinary carbonic anhydrase 3 not only reflects existing injury but also predicts progression or response to intervention. Keywords:Carbonic anhydrase 3, urine biomarker, renal interstitial injury, atherosclerotic renal artery stenosis, Xiufeng Li, BMC Nephrology