The Creatinine Clearance (CrCl) Test assesses kidney function by measuring how well your kidneys filter creatinine, a muscle waste product, from your blood into urine, using both blood and a 24-hour urine sample to compare levels. It helps diagnose kidney disease, monitor its progression (especially with conditions like diabetes or high blood pressure), and guide treatment, with lower results indicating poorer kidney filtration, though factors like muscle mass affect it