Do I need to fast for blood test?

I believe everyone is familiar with routine blood tests. Routine blood tests include a lot of content. There are many precautions before doing a routine blood test, such as paying more attention to diet, especially not smoking and drinking. You must ensure enough sleep the night before the test and never overwork, otherwise it will affect the test results. So does a routine blood test need to be done on an empty stomach?

Do I need to fast for blood test?

Generally speaking, a routine blood test requires fasting. You should be on an empty stomach before the test, but fasting is not as simple as skipping breakfast. You should avoid eating greasy food the night before the examination, and you should fast after 8 o'clock. If you still have a midnight snack at 12 o'clock, you will not be able to ensure that you are on an empty stomach when your blood is drawn.

On the morning of the physical examination, no beverages, including juice and milk, are allowed except boiled water. If you want to get better test results, it is best to eat a basically vegetarian diet starting three days before the test. Why do we need to fast for routine blood tests? What are the benefits of fasting before a blood test? An expert from the hospital's liver disease department said that fasting before a routine blood test has the following three benefits: Each test uses a different testing method and the normal values ​​are also different. Normal data is obtained by measuring the fasting blood of a large number of normal people.

Because the body is relatively in a basal metabolic state when fasting, the influence of factors such as food is eliminated, and the properties are relatively stable, it can reflect the true situation of human blood. After statistical processing of many test results, the normal value detected by this method was obtained. Therefore, when patients undergo blood tests, fasting blood tests should also be drawn. Only such test results are reliable, can truly reflect the patient's actual condition, and can provide valuable evidence for diagnosing the disease.

After eating, food is chewed in the mouth, digested and absorbed by the gastrointestinal tract, enters the blood, and is then transported to various tissues and organs throughout the body by the blood. Therefore, certain components in food enter the blood and increase the concentration of certain components in the blood. Thus, the test results may be incorrect.

Other precautions for routine blood tests

Before the test: (1) Do not eat greasy or high-protein foods and avoid drinking large amounts of alcohol the day before blood collection. The alcohol content in the blood will directly affect the test results.

(2) You should fast for 12 hours starting at 8:00 pm the day before the physical examination to avoid affecting the test results.

(3) When drawing blood, you should relax to avoid blood vessel constriction due to fear, which will increase the difficulty of blood collection.

After the examination: (1) After drawing blood, apply local pressure on the needle hole for 3-5 minutes to stop the bleeding. Note: Do not rub to avoid causing subcutaneous hematoma.

(2) The pressing time should be sufficient. The clotting time varies from person to person, and some people need a little longer to clot. Therefore, if you stop applying pressure immediately when the surface of the skin seems to be not bleeding, the bleeding may not stop completely, and the blood may seep into the subcutaneous layer, causing bruises. Therefore, pressing for a longer time can completely stop the bleeding. If there is a tendency of bleeding, the pressing time should be prolonged.

(3) If you experience symptoms of needle phobia such as dizziness, blurred vision, fatigue, etc. after blood draw, you should lie down immediately and drink a small amount of sugar water. Wait until the symptoms are relieved before undergoing a physical examination.

(4) If local bruising occurs, apply a warm towel for 24 hours to promote absorption.