1. Reasons for fasting
Fasting is to ensure the objective and accurate test results. Many blood tests need patients? Fasting This is because after ordinary meals, blood triglycerides will increase by 50%, blood sugar will increase by 15%, alanine aminotransferase and blood potassium will increase by 15%.
There is a time limit for fasting, and the general standard of fasting is 8? /kloc-no calorie intake for 0/4 hours. Generally, I don't eat breakfast on the morning of the exam. If the fasting time is too long, exceeding 18 hours, the body is already in a state of mild hunger. In the state of hunger, many components in the blood will change, which will also have a bad influence on the test results.
2. Items that need fasting
blood sugar
Gastroscope and colonoscopy: After eating food in the stomach, it will affect the vision of gastroscope. If nausea and vomiting occur, there may be a danger of suffocation; The intestines should be drained clean to ensure a clear vision.
CT: Abdominal CT must be on an empty stomach, such as chest CT, skull CT and limb CT, but not necessarily on an empty stomach. But if it is definitely enhanced CT, then no matter which part is examined, it must be empty stomach!
B-ultrasound: Eating will affect bile excretion of gallbladder, changes of liver cells and digestive organs, so we must have an empty stomach before doing B-ultrasound examination of liver, gallbladder and spleen in abdomen. Others don't need strict fasting, for example, they don't have much impact on the urinary system or gynecological system.
Blood drawing: Not every project requires fasting blood drawing. Blood lipid testing is to avoid the illusion of hyperlipidemia caused by dining problems, and it takes at least three days of light diet. As for blood sugar, it is even stricter. General hospitals divide blood sugar into fasting blood sugar, postprandial blood sugar 1 hour and postprandial blood sugar for 2 hours. These time requirements are a standard to finally judge the test results (such as OGTT/ steamed bread test to determine the type of diabetes). In addition to blood lipids, there is no problem with the liver function and kidney function of non-fasting blood.
3. Can I drink water on an empty stomach?
Generally speaking, drinking water on an empty stomach is not recommended. It is necessary to abstain from food and water within ten to twelve hours. If you are very thirsty, you can drink a small amount of water to ensure the normal water supply of your body. Don't drink too much, lest water dilute the blood and affect the physical examination results.