Our physical examination department receives many examiners requesting entry every day, and most of them come in a state of hunger and thirst, with a higher percentage of urine abnormalities due to excessive water abstinence. In fact, for many people who do not do abdominal ultrasound, there is no need to abstain from water, because generally normal water consumption should not affect the results of blood sampling tests. Imagine the fruit and vegetables in the field, without water will wilt, for people, lack of water will cause blood concentration, insufficient volume, inadequate perfusion of various organs, hypotension and tachycardia may occur, it is easy to urinate less, so that the urine is overly concentrated and abnormal. The absorption of water is very fast, generally speaking, it takes 4-6 hours for the stomach to empty food, while the absorption of water does not take that long, so when you calculate the time of physical examination, it is enough to control the intake of water for 4 hours. In addition, for ladies, menstruation and vaginal discharge can also affect the urine results.