Kidney is one of the important organs of human body, its function is mainly to secrete and excrete the waste of body metabolism; regulate and maintain the stability of the body’s internal environment. A variety of diseases can affect the kidneys. By checking the changes of kidney function indicators, it helps doctors to detect and diagnose diseases in time. The common tests of kidney function in hospitals are serum urea nitrogen, blood creatinine, uric acid, etc. 1.Serum urea nitrogen 1.Increased serum urea nitrogen is mainly found in: (1) various kidney lesions such as chronic nephritis, pyelonephritis. (2) Ureteral, bladder and prostate diseases, such as ureteral stones, tumors, prostate disease, etc., so that urinary tract obstruction caused by a significant reduction in urine volume or no urine, can also cause an increase in serum urea nitrogen. (3) Other things such as dehydration, increased protein catabolism, upper gastrointestinal bleeding, etc. may also cause an increase in serum urea. 2.Decrease in serum urea is mainly seen in toxic hepatitis, acute liver atrophy, etc. Second, blood creatinine 1, increase is mainly seen in the kidney itself lesions such as nephritis. When the glomerular filtration function decreases to 30% to 50%, the value of blood creatinine only rises significantly. When blood creatinine 176-355μmol/L, it indicates moderate to severe kidney damage. When blood creatinine and urea increase at the same time, it indicates serious kidney function damage and poor prognosis. 2. Decrease is mainly seen in progressive muscular atrophy, leukemia, anemia, etc. 3.Increased uric acid is seen in 1.Gout. 2.Kidney lesion. 3, malignant tumor. In addition, there are some other indicators such as urine microalbumin, β2 microglobulin, retinol binding protein, urine albumin, etc. can reflect the kidney function.