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 (plasma) uric acid concentrations range from 150 to 416 μmol/L for men and 89 to 357 μmol/L for women, approaching that of men after menopause. A lower than normal uric acid concentration is considered low uric acid. The liver is the main site of uric acid production, except for a small portion of uric acid that can be further broken down in the liver or excreted with bile, the rest is excreted from the kidneys. Uric acid can pass freely through the glomerulus and can also be excreted by the renal tubules, but about 90% of the uric acid that enters the original urine is reabsorbed back into the blood in the renal tubules. Therefore, the cause of uric acid bottom is mainly due to various causes of renal tubular reabsorption of uric acid, which leads to a large loss of uric acid from the urine, as well as a decrease in uric acid production due to serious impairment of liver function. For example, acute hepatic 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, low uric acid means that the blood uric acid concentration is lower than the normal value, mainly due to two main reasons: the decrease of uric acid production caused by serious impairment of liver function and the decrease of uric acid reabsorption by renal tubules.