Serum creatinine is a poor indicator of kidney function due to its dependence on muscle mass and other variables.

“we use serum creatinine as kind of our best guess at kidney function there's lots of reasons why that's a poor indicator you know it's it's not it's very dependent on muscle mass and and other variables that that um allow you that prevent you from using some sort of kind of normalized number as an acceptable range there are more sensitive markers as you alluded to there there's now that i think fortunately finally being recognized the whole question of how creatinine and gfr and race interacts and how that needs to be accommodated for”