08/09/2026
A lower creatinine usually looks like better kidney function—but creatinine can also fall when someone loses muscle mass.
This video raises that concern in the context of the TEMPO trial used to approve tolvaptan for PKD, and asks why cystatin C data—another kidney-function marker that is less dependent on muscle mass—was not published.
It’s an important question about how treatment effects are measured and interpreted. What do you think the cystatin C results could add to the picture?