What is the fasting physical examination for? Why should the physical examination be on an empty stomach?

I believe many people have had physical examination experience, and doctors sometimes ask them not to eat the next morning, but to have an empty stomach examination. Even said not to drink water, why?

Check items need to keep the stomach clean.

For example, gastrointestinal endoscopy, if there is food residue, will affect the observation, so you need to keep your stomach in a good detection state by fasting. In addition, barium sulfate should be taken in barium meal to make the digestive tract more obvious under X-ray. If there is food jam, there will be dark shadows, so you need an empty stomach before barium meal.

Examination items will be affected by diet.

On an empty stomach, the human body is in a relatively stable metabolic state, which can exclude the influence of diet and other factors, so an empty stomach blood test can reflect the real situation in human blood. For example, the blood glucose and blood lipid test, if eaten, the body's metabolism will cause the blood glucose and blood lipid to rise, so that the normal blood glucose and blood lipid values can not be measured. The intake of protein will affect the test results of liver function; Sugar intake will affect the test results of blood sugar; Excessive purine intake will affect the test results of renal function. Therefore, any physical examination items that will affect the observation effect or the observation result because of eating for a short time, the doctor will ask the medical examiner to have an empty stomach.

These common items require fasting examination.

Fasting physical examination is mainly aimed at special items that are easily affected by diet in the short term. It generally involves the examination of digestion and physiological metabolism, and it is necessary to go to the physical examination on an empty stomach. Such as blood sugar, blood lipid, some biochemical tests, abdominal ultrasound, barium meal, gastrointestinal endoscopy and so on. These are common items of physical examination, so as long as these items are included in the examination, you need to go to the physical examination on an empty stomach. Specific matters only need to follow the doctor's instructions. If you feel unwell, you should also ask the doctor in time.

How can an empty stomach be empty?

It is advisable to stay overnight on an empty stomach without calorie intake. Specifically, it is about 8~ 14 hours, and it is not good to be on an empty stomach for too long. For example, the determination of blood sugar and blood ketone bodies in hunger can not be used as a reference for diagnosis. Generally speaking, I stopped eating after dinner the night before. The best time for physical examination is around 8 am the next day. Don't eat big fish and meat the night before, and don't eat snacks, so as not to affect the accuracy of the physical examination. Don't eat the next morning, and eat after the physical examination.

Can't you drink water on an empty stomach?

Generally, you can drink water on an empty stomach, so as not to feel thirsty. Even if you draw blood on an empty stomach, you can't drink water at all. If the intake of water is too small, the human body will enter a state of dehydration, leading to deviations in physical examination results. For example, it is easy to measure the deviation result of "blood thickness" when water is banned for a long time. And special physical examination items are not allowed to drink water. It is forbidden to drink water such as painless gastrointestinal endoscopy, which is easy to cause coughing and suffocation. Therefore, in addition to the doctor's advice not to drink water, other physical examination items can be properly drunk with pure water. Note that it is pure water. Other coffee, drinks, tea drinks, wait until the physical examination is over. Drinking drinks will affect the results of blood biochemical tests and easily lead to misjudgment.

These tests do not require fasting.

Yes, not all physical examinations require an empty stomach. For example, it doesn't matter much whether you measure your height, measurements and weight on an empty stomach. There are also MM who insist on measuring their weight on an empty stomach in order to make their weight appear relatively low.

Bian Xiao just wanted to say happy. And our common three routine physical examination items, blood routine, stool routine and urine routine, are not affected by short-term eating, so doctors will not ask for fasting. Similarly, examinations that do not involve digestion and physiological metabolism do not require fasting, such as chest X-ray, electrocardiogram and CT.

You need an empty stomach physical examination to do these five points well.

Eat normally the day before the physical examination, don't deliberately eat less, don't overeat and don't drink alcohol.

② Don't eat midnight snack at night, and start to fast after dinner, and don't add meals.

(3) Don't eat breakfast the next morning, don't drink plenty of water, and avoid excessive exercise. If you have special requirements, you need to ban water.

④ Prepare some food and water, and replenish energy and water in time after the physical examination.

⑤ If you feel unwell, such as hypoglycemia, you should postpone the physical examination and eat immediately.