Blood tests for kidney function mainly include blood creatinine, urea nitrogen, uric acid, as well as β2-microglobulin, cystatin C and other items. Kidney is an important organ of human body and its main functions include producing urine, removing metabolites from the body, regulating water and electrolytes, acid-base balance and so on. Through the above several tests, it can reflect the kidney function. For example, creatinine, urea nitrogen and cystatin C usually reflect the excretory function of the kidneys; β2 microglobulin reflects the glomerular filtration function. If the results of these tests are abnormal, renal insufficiency is the most common cause. In clinical practice, in addition to blood test, ultrasound, 24-hour quantitative urine protein test, urine routine and other items are also needed to help clarify whether there is kidney disease, so as to facilitate further examination to identify the cause of the disease and get timely treatment.