In outpatient primary care settings, would you recommend routinely checking Cystatin-C as a marker of renal function in older adults?  

I probably would not recommend routine Cystatin-C testing for all older adults, but would consider it in certain scenarios where eGFR may be inaccurate or misleading. In geriatrics, sarcopenia and low muscle mass often make serum creatinine a less reliable marker of true kidney function. Cystatin-C ...

There isn't much literature guidance for this question. In general, I don't think we're at the point of using this as routine testing. Rather, I think it is useful in certain clinical situations, such as eGFR at the border of CKD staging or symptoms that seem out of proportion for eGFR, particularly...

One more piece to the story - Estrella et al., PMID 41202182.