The Urine ACR (Albumin-to-Creatinine Ratio), also known as Microalbumin Creatinine Ratio, is a test that measures the amount of albumin (a protein) in the urine relative to creatinine (a waste product from muscle metabolism) in the same urine sample. The ratio helps assess kidney function, specifically the presence of early-stage kidney damage, particularly in conditions like diabetes or hypertension.