Microglobulin can be divided into two types: blood β2 microglobulin and urine β2 microglobulin. The normal value of blood β2 microglobulin is 2.4-2.7 mg/mL, while the normal value of urine β2 microglobulin is 31.5-100ug/24 hours. Blood β2 microglobulin and urine β2 microglobulin are both indicators of kidney function. Elevated blood β2 microglobulin is commonly found in patients with decreased glomerular filtration function, such as those with primary and secondary factors leading to kidney diseases, such as glomerulonephritis, hypertensive nephropathy and diabetic nephropathy. In addition, elevated blood β2 microglobulin is also common in patients with malignant tumors and rejection after kidney transplantation. Elevated urine β2 microglobulin is often an indicator of renal tubular impairment, and elevated urine β2 microglobulin is often indicative of renal tubular impairment, as well as elevated urine β2 microglobulin when upper urinary tract infections occur.