Urine ACR is called urine microalbumin to creatinine ratio, and its clinical significance is to determine early kidney injury, i.e., to measure 24-hour urinary albumin excretion for early screening of diabetic nephropathy, hypertensive kidney injury, glomerulonephritis, and chronic interstitial kidney disease. Results in the range of 30-300 mg/24 hours suggest microalbuminuria, which is an early manifestation of kidney disease. Lesions at this stage are usually reversible and this test provides an early indication of early kidney disease. This test can also determine the presence of endothelial cell damage in patients with coronary artery disease, which has a poor long-term prognosis. However, this test should be performed 2-3 times a year to improve its positive rate and accuracy. In view of this, it can also be called one of the five tests for premature renal failure, which shows its clinical importance.