Alpha 1-microglobulin is a low molecular weight protein, synthesized by human liver and lymphocytes, and is present on the surface of various body fluids and lymphocytes in the body. Under normal conditions, free α1-microglobulin in blood can be filtered through the glomerular filtration membrane, about 95%-99% is reabsorbed and metabolized in the proximal tubule, and only a very small amount is excreted from the urine, while bound α1-microglobulin cannot pass through the glomerulus and its concentration in the urine is 0. In clinical practice, by measuring α1-microglobulin in blood and urine, it can indirectly reflect the glomerular filtration function and It is a relatively sensitive indicator of renal tubular reabsorption function. It is generally believed that the increased concentration of α1-microglobulin in blood and urine indicates the following: 1. reduced tubular reabsorption and metabolic function, such as acute and chronic interstitial nephritis. 2. impaired glomerular filtration function, such as the early stage of glomerulonephritis caused by various reasons, including primary glomerulonephritis, lupus nephritis, diabetic nephropathy, hypertensive kidney damage, etc.