Urine NAG refers to the enzyme N-acetyl-β-D aminoglucosidase in the urine test, which is mainly used to determine whether there is tubular damage or not. N-acetyl-β-D aminoglucosidase is found in a wide variety of tissues, and because of its large molecular size, it is usually unable to pass through glomerular filtration into the urine. Therefore, only low levels of N-acetyl-β-D aminoglucosidase are usually found in normal human urine tests. N-acetyl-β-D aminoglucosidase is abundant in kidney tissue, especially in the epithelial cells of the renal tubules, and an elevated level of N-acetyl-β-D aminoglucosidase in the urine suggests that there may be kidney damage (glomerular damage, tubular damage). Usually, tubular injury is more common, such as acute tubular necrosis and tubular acidosis. If the patient needs to improve the N-acetyl-beta-D aminoglucosidase in the urine test, it is recommended to go to a regular hospital and have the test results prescribed and evaluated by a professional doctor.