Many people understand that drawing blood on an empty stomach is a hungry meal, but in fact, drawing blood on an empty stomach is not just a hungry meal, but it takes 8 hours to draw blood, and drawing blood is usually carried out in the morning, because physiological activities during the day will also affect the test results.
The purpose of fasting blood drawing is to ensure the accuracy of venous blood laboratory test results. General fasting blood tests include: liver function, renal function, blood sugar, blood lipid, blood biochemistry and hemorheology, as well as gastrointestinal endoscopy and abdominal ultrasound.
If you only do routine blood tests and other items, eating within a few hours or even a day will not change the number of blood cells to be tested, so you don't need to be fasting when doing routine blood tests and other items. Chest CT, electrocardiogram and other items do not involve digestion and metabolism, and generally do not need fasting.
Fasting blood test is because the reference range of many test items comes from the test results of fasting blood drawn by healthy people. If a person draws blood on an empty stomach, the reference range is meaningless, which seriously affects the interpretation of the results.
In addition, after eating, digested food will make blood turbid and chyle, that is, fatty blood. Many examination items need to be compared, and chylous blood will affect the examination results. Therefore, if the blood received by the laboratory is chylous blood, it will generally be returned and blood will be drawn again for re-examination.
If blood is taken on an empty stomach after eating, the concentration of protein, sugar, purine and other components in the blood will increase significantly, which will seriously affect the test results. For example, eating high-protein food will increase the value of urea nitrogen and serum creatinine, resulting in the illusion of kidney function problems.
If you eat a lot of high-fat food the day before the physical examination, the triglyceride will increase obviously, and the accuracy of many tests such as liver function will be affected, so it is recommended to avoid greasy diet three days before the physical examination. In addition, alcohol will also affect many test results, such as triglycerides, transaminase, uric acid, etc., so don't drink alcohol before testing.
Can you still drink water before drawing blood on an empty stomach? Does anyone else ask if you can't drink water on an empty stomach? It's okay to drink a little. If you drink hundreds of milliliters of water at a time, you can't. It is no problem to drink boiled water in the morning of physical examination. Some people really listen to blood drawing on an empty stomach for more than ten hours without drinking water. At this time, some people have been dehydrated, which also has an impact on the test results.
But don't drink drinks, tea, coffee and other drinks before drawing blood on an empty stomach. The sugar, caffeine and other ingredients contained in these drinks will affect the test results. Just drink a little boiled water.
Four preparations should be made before blood drawing, and the test results are reliable. It is best before 1 in the morning. It should be noted that fasting for a long time will reduce blood sugar and affect the test results, so we should grasp the time, generally fasting for 8 hours, fasting time should not be too long, and it is best to draw blood before 10 in the morning, which is also the blood drawing time in most physical examination centers.
2. Don't take vitamins or other drugs. Taking large doses of vitamin C will lead to the deviation of urine sugar results. In addition, about 65,438+0,500 drugs interfere with blood tests, such as antibiotics and anti-tuberculosis drugs.
Don't stretch your clothes too tight. Try to wear loose clothes when drawing blood, and don't wear small or tight clothes, so as to avoid rolling up your sleeves when drawing blood, or causing blood vessel hematoma at the blood drawing site because your sleeves are too tight after drawing blood.
4. Don't do strenuous exercise. Because strenuous exercise affects the internal environment of the human body, it raises blood pressure and speeds up the heart rate, such as long-distance running, boxing and lifting iron. , which has a great influence on the test results.
After blood drawing, there are still platelets that are not coagulated at the blood drawing place, resulting in continuous bleeding. At this time, you can press the part with a cotton swab or finger until the bleeding stops.
Pressing usually takes 3 to 5 minutes, and it takes longer for the elderly or people whose blood is difficult to coagulate. Some people think that pressing 1 min is enough, but it is wrong and easy to cause bleeding. Some people wake up the next day and find that the bleeding place is swollen, which is why. It should be noted that you can only press it, not knead it. Friction bleeding places will not only stop bleeding, but also accelerate the outflow of blood and increase the difficulty of stopping bleeding.