Creatinine

What it is

Creatinine is a waste product of muscle metabolism, filtered by the kidneys at a relatively constant rate. Because production is fairly constant, blood creatinine levels reflect kidney filtration ability (GFR) more directly than urea.

Why it matters

Several chemotherapy agents are nephrotoxic (cisplatin being a major example). Monitoring creatinine through treatment cycles is essential — a rising creatinine signals kidney stress that may require dose adjustment or additional kidney protection protocols.

How to test

Standard renal function panel.