Blood uric acid must be checked on an empty stomach for the following reasons: 1. Uric acid is the end product of purine metabolism, mainly produced by the cellular metabolism of nucleic acids and other purine compounds and the enzymatic decomposition of purines in food. Food-induced uric acid production is proportional to the purine content of food, high-fat, high-sugar foods rich in purines, including mainly animal offal, especially liver, kidneys, heart, broth and seafood, such as anchovies. These foods can cause an increase in the production of uric acid, thus affecting the test results, so it should not be consumed before the test. 2, uric acid about 2/3 through the kidney excretion, a lot of water can dilute the blood uric acid concentration, increase the excretion of uric acid, so should not drink a lot of water when testing the blood uric acid concentration. Alcohol can both increase the production of uric acid and reduce the excretion of uric acid, thus increasing the blood uric acid concentration, so it is not advisable to drink alcohol before testing the blood uric acid concentration. Therefore, patients who need blood uric acid test should abstain from purine-rich diet for 3 days, avoid drinking alcohol and large amount of water the day before the test, and fast for more than 12 hours, so that the test can be more realistic and meaningful. In addition, because of the large fluctuations in blood uric acid, the test should be repeated at least twice.