Why do you have to go on an empty stomach and what happens if you eat in the morning?

Generally speaking, most of the laboratory tests that require fasting blood are biochemical tests, such as liver function, blood sugar, protein, lipids, and electrolytes potassium, sodium, chloride, etc. The reference values of biochemical tests are obtained by statistical processing based on the fasting blood of healthy individuals. This is because the venous blood taken before meals in the early morning of the same day has relatively stable biochemical components, and the measured values can reflect the biochemical changes of the body more realistically.

If blood is collected after eating, the biochemical components in the blood (such as blood glucose, blood lipids, etc.) will change temporarily, and the measured results cannot reflect the real condition of the body, and cannot be compared with the reference value measured in fasting blood, so it is impossible to make accurate clinical judgments. After meals, blood sugar and blood lipids will increase, which will affect the accuracy of the results. The aminotransferases of normal people rise, and the judgment of "abnormal" is obtained; The number of people with abnormal aminotransferases is even higher.

Although it is said to be fasting, there is no need to abstain from water, and a small amount of water drinking generally does not have a significant effect on the test. However, drinking large amounts of water should be avoided as this can cause blood thinning. Affects the results of tests such as blood counts, making them lower than true.

Is there also the best time to draw blood on an empty stomach? Don't ignore the two precautions before the physical examination, so as not to affect the test!

Children need to be fasting for blood tests such as liver function, kidney function, blood sugar, and blood lipids; If the child has a blood test for routine blood tests or allergens and trace elements, there is no need to fast. Children with colds, coughs, and fevers can be tested through blood tests to see if the child is a viral infection or a bacterial infection, and then treat the symptoms. For the general fasting test for children, you need to get up after 12 o'clock the night before to get up early without eating and drinking, and go directly to the hospital for blood testing.

Influential. After eating, different components of food will affect the test results to varying degrees. Expert.

A genus in which blood is collected after eating.

After the food is decomposed and enters the bloodstream, transaminases and triglycerides increase the serum concentration, which affects the test results of various indicators. For example, after eating pig blood and other foods, fecal occult blood can be falsely positive; After eating in the morning, the gallbladder contractions, and during ultrasonography, it affects the visualization and it is easy to miss the lesion.

In addition, after eating, food travels into the gastrointestinal tract, and abdominal ultrasound will also affect the development to a certain extent, making it more difficult to distinguish normal abnormalities. Therefore, such as blood draw, abdominal ultrasound, etc., it is usually recommended to do it on an empty stomach.

Precautions: For some patients with chronic diseases who need to take medication for a long time, some people are worried that the medication they take will affect the results of the physical examination and stop taking the medicine on the day of the physical examination, which is actually very dangerous. Generally speaking, for people with chronic diseases who need to take medication for a long time, they can also take the medicine as usual before the health check-up and inform the doctor during the check-up.

Patients with chronic diseases such as diabetes should carry the usual medications with them, and take them after the fasting check-up, so as not to delay for too long and cause hypoglycemia.

If there is an impact, it should be that you should not eat or drink after 8 o'clock in the evening before the physical examination, so that the results of the physical examination on the next day are accurate.

It doesn't affect but don't eat water or drink it Drinking water can affect the concentration of body fluids and blood The blood test has an impact on the secretion of the digestive system and liver system It affects the accuracy of the test.

If it doesn't affect much, don't worry too much, but don't eat or drink water from now on.

When fasting, the body is in a relatively basal metabolic state, which can exclude the influence of factors such as diet, and the test results are more accurate; Eating breakfast will have a certain impact on the data, because after eating, the body's liver, kidneys, blood lipids and blood sugar will undergo certain changes.

This is because the blood drawn on an empty stomach does not affect the final value; If you eat breakfast, it will have an impact on the data, which will lead to inaccurate data.

Because if you eat, the data is inaccurate; Eating breakfast has a very big impact on the data, so doctors usually ask you to have blood drawn in the morning when you don't eat breakfast.

Physical examination is very necessary for all of us, especially the middle-aged and elderly, because people will have various diseases when they reach middle age, at this time it is best to have an annual physical examination, so that they have a general understanding of their body, what diseases can also be compared to the fiber cover**, the physical examination is generally to draw blood, that blood to draw fasting? What are the effects of having blood drawn after eating?

1. Do I have to have an empty stomach to draw blood?

Blood draws do not have to be on an empty stomach.

Whether to take blood on an empty stomach is for specific examination items, such as the routine blood examination in the hospital, the examination items are mainly related to the counting of various cells and immune proteins, and it does not matter whether you eat or not without checking blood lipids and blood sugar.

2. Is it better to have an empty stomach or eat and draw blood

It is good to draw blood on an empty stomach.

For the accuracy of the examination, it is best to draw blood on an empty stomach, because the standard of many examination items is determined by the measurement of fasting blood draw, and the blood sugar and blood lipids in the blood after eating are high, and the blood test results may affect the accuracy of the examination items.

3. Which examinations require fasting blood draw

In the medical mask fasting blood glucose, blood lipids, renal function (mainly blood urea and blood uric acid), liver function (mainly bilirubin, aminotransferase), blood viscosity, fasting examination and other functional tests of the blood test must be strict fasting, and coagulation function, glycosylated hemoglobin, blood routine, blood sedimentation rate, immunity all laboratory test items such as hepatitis B trilineage, hepatitis full set, various hormones, myocardial markers, thyroid function, tumor markers, autoantibodies, rheumatoid and other examinations require patients not to eat high-fat food. Not explicitly asked for fasting.

4. Which examinations require blood to be drawn after meals

There are pre-meal blood test items, and there are also some tests that need to be eaten, such as half-and-half after meals, 1, and hourly blood sugar, C-peptide, insulin, etc., which need to check blood sugar or specific enzyme function, and blood needs to be drawn after meals to find out the specific situation.

5. Pay attention to diet before physical examination

1. Eat a light diet the day before the physical examination, avoid eating salty, sweet, animal offal and other high-fat foods, and avoid drinking liquor.

2. It is best to fast (including water fasting) for more than 8 hours before the physical examination, so as not to affect the test results of blood glucose, blood lipids, urea nitrogen, liver function and other indicators; On the morning of the physical examination, you should have an empty stomach, fasting and water.

Causes abnormalities in blood test results.

For example, eating foods high in fat can significantly increase triglycerides several times; Consuming foods high in sugar can cause a rapid rise in blood sugar within two hours. These can affect the composition of the blood, causing a "misjudgment".

After eating in the evening of the first day to the early morning of the next day, the fasting time is more than 10 hours, and various substances in the body have reached relative stability and balance, and the food factors have basically no effect on the blood composition, and the blood draw can get relatively stable and accurate results at this time.

Therefore, try to exercise as much as possible before blood drawing, do not eat food, keep an empty stomach, drink a small amount of water, and take it on time except for certain medications. Failure to do so will interfere with the results of some experiments.

If we eat before the test, different components of the food we eat will have different degrees of impact on the test results. If blood is collected after eating, the food will break down and enter the bloodstream, which can increase the serum concentration and affect the test results of various indicators.

Because it is easy to affect the results of blood tests after eating, many items of blood sampling in general physical examination require fasting, which is more accurate.