Every nephrologist knows about serum creatinine, eGFR, albuminuria, proteinuria. We use them to assess disease activity. But do we really assess disease activity with them? eGFR can be low and albuminuria or proteinuria can be high because of chronic and potentially irreversible changes, like glomerulosclerosis and tubulointerstitial fibrosis, changes that might not be amenable to treatment. How do we know which patient needs more treatment if what we are picking up with established markers might be fibrosis. Well, these questions might become old-fashioned quickly. Let us introduce you to DKK3, a new urine biomarker which could finally identify patients with ongoing kidney injury that might benefit from more treatment. Have a listen to our new ERA podcast with Danilo Fliser, explaining what DKK3 is and why we should all probably begin measuring it.