The Development of Urinary Biomarkers for Kidney Disease Is the Search for Our Renal Troponin

The practice of nephrology is long recognized to treat and comfort on the basis of a blend of science and art. As nephrologists, we do an amazing job of monitoring kidney function with rather rudimentary measures such as serum creatinine and urine output. When patients ask what are the “normal” values for each of these measures, we all answer in a similar and somewhat nonspecific manner reflecting the “art” of interpretation: What is normal creatinine? Answer: It is like golf: High is bad, low is good. What is a normal amount of urine? Answer: Depends on how much you drank and ate. The new field of biomarkers for kidney injury or disease is an exciting and rapidly advancing scientific area. Recent developments in the study of several urinary biomarkers of kidney injury have focused on NGAL, NAG, and KIM-1. Two articles in this issue of JASN are part of a growing literature that will shift the balance between the art and science of understanding—shifting toward new evidence that anticipates changes in kidney function more reflective of better science.1,2 As we read this rapidly growing literature and seek out our “renal troponin,” we can take a lesson from our cardiology colleagues: Our ultimate goal is to identify patients with a clinical syndrome earlier to initiate promptly a therapy that ultimately affects …