Albumin/Creatinine Ratio (ACR), Urine:- The urine albumin-to-creatinine ratio (ACR) is a test that measures the amount of albumin (a type of protein) relative to creatinine (a waste product) in a urine sample. It is used to detect early kidney damage and monitor kidney function, especially in people with diabetes, high blood pressure, or other conditions that can affect the kidneys.