Uric acid is the end product of purine metabolism and is mainly produced by the enzymatic breakdown of nucleic acids and other purine analogues from cellular metabolism and purines from food. Adult enzymatic serum uric acid concentrations range from 150 to 416 μmol/L in men and 89 to 357 μmol/L in women, and approach those of men after menopause. Uric acid concentration higher than normal is called high uric acid, and there are two main types of causes: increased uric acid production and decreased uric acid excretion, and sometimes both of them coexist. Increased uric acid production: This includes both high purine dietary intake and increased metabolic production of endogenous purines. Food-induced uric acid production is proportional to the purine content of food, and purine-rich foods include animal liver, kidney, anchovies, etc. The increase of endogenous purine metabolism in the body is mainly related to the synthesis and decomposition of purine. Decreased uric acid excretion: About 2/3 of uric acid is excreted through the kidneys, and the remaining 1/3 is excreted through extrarenal pathways such as the intestinal tract and biliary tract. About 90% of patients with persistent hyperuricemia have defects in renal processing of uric acid and show reduced uric acid excretion, including reduced glomerular filtration rate, increased tubular reabsorption, reduced tubular secretion and urate crystallization. Uric acid concentration is lower than the normal value as low uric acid: mainly due to various causes of renal tubular reabsorption impairment of uric acid, large loss of uric acid in the urine, and serious impairment of liver function to reduce uric acid production. Such as acute liver necrosis, hepatomegaly, etc. In addition, chronic cadmium poisoning, use of sulfonamide and high dose glucocorticoids, congenital defects in xanthine oxidase and purine nucleotidase, which are involved in uric acid production, can also cause a decrease in blood uric acid. Therefore, the normal value of uric acid is 150~416μmol/L for men and 89~357μmol/L for women. High or low uric acid concentration is abnormal, which should be taken seriously, and the cause should be identified and treated actively.