Urine Albumin to Creatinine Ratio or ACR

Albumin is a protein that is present in large amounts in the blood. When kidneys are working properly, only tiny amounts of albumin leak through into the urine. In kidney failure (the last stage of a slow process of decline in kidney function) large amounts of protein leak into the urine. A long time before this amount of damage, small changes in the blood-filtering parts of the kidney allow very small but abnormal amounts of albumin to leak through, usually as a result of having diabetes. Too little albumin is present to be detected by the usual simple urinalysis with a test strip or dipstick method. (It used to called “microalbumin” because of its low concentration, not because it is a smaller molecule).

You will be asked to collect either an early morning or random sample of urine in which albumin will be measured by a sensitive method and related to the creatinine concentration and reported as an albumin/creatinine ratio or ACR. The ACR has been shown to be of greater diagnostic value than the measurement of albumin alone in timed urine samples, largely because of difficulties in making accurately timed urine collections.