Does a blood group test require fasting?

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Blood group test to know each person's blood group. In the types of blood tests, blood group testing requires fasting depends on the doctor's orders.
Fasting before a blood test is when the patient is asked not to eat or drink anything but water before the blood test. However, not all blood tests require fasting before the test, usually, if so, only fasting for a short time.

1. Why should fasting before blood test?

There are some tests that give accurate results only when the patient fasts 4-6 hours before the test or does not eat breakfast after a night of waking up. The reason is that after eating, the nutrients in the food will be converted into glucose for absorption by the intestines and converted into energy to feed the body. At that time, it will make the blood sugar or fat level rise, if the blood test will give inaccurate results.

2. Does a blood group test require fasting?

Depending on the type of blood test intended, the patient will be asked to fast or not.
For blood group test, the purpose of doing blood test is to know the blood group. There are many blood types, the classification of blood groups is based on the type of antigens present on the surface of red blood cells in the blood. Currently, science has found many different types of specific antigens, however, the ABO type and the Rhesus type are the most important. These antigens are regulated by the genes each person receives from his or her parents. Therefore, blood group testing does not require fasting.
Commonly known major blood groups are:
Blood group A+: Has A antigens and Rhesus antigens. Blood group A-: Has A antigens and no Rhesus antigens. Blood group B+: Has B antigens and Rhesus antigens. Blood group B-: Has B antigens and no Rhesus antigens.

Blood group AB+: has A, B and Rhesus antigens. Blood group AB-: has A, B antigens and no Rhesus antigen. Blood group O+: does not have A or B antigens but has Rhesus antigens. Blood group O-: no A, B or Rhesus antigens.

3. Types of blood tests that require fasting

3.1. Blood sugar test

Besides the blood type test, the purpose of a blood glucose test is to measure blood sugar to see if it is normal, and can be used to diagnose diabetes.
To ensure accurate results, patients need to fast or drink (except water) for about 8 to 10 hours before the test. Fasting helps ensure accurate blood sugar readings. These results are used by your doctor to diagnose or rule out diabetes.

3.2. Blood iron test

In addition to a blood type test, a blood iron test measures the amount of iron in the blood. Test results will help identify diseases caused by iron deficiency, such as anemia.
In some foods containing iron, when eaten, iron is absorbed very quickly from the food into the bloodstream. So, if you eat before the iron test, it will give inaccurate results. Therefore, it is necessary to avoid using dietary supplements or vitamins before the test, as this can affect the accuracy of the results.
To ensure accurate results, patients are asked not to eat anything the morning before the test.
In case you are taking iron tablets or multivitamin supplements containing iron, it should be discontinued 24 hours before the test so as not to affect the results.

3.3. Blood fat test

Different from blood group test, blood fat test to determine the indicators of blood fat status including total cholesterol, HDL cholesterol, LDL cholesterol and triglycerides. High levels of LDL-cholesterol and triglycerides mean that the patient is at high risk of cardiovascular problems.
Blood lipid testing is usually recommended for people over 45 years old and should be tested every 5 years or patients with hypertension and diabetes.
If the patient has a history of cardiovascular disease, it is recommended to have this test more often to measure and control the amount of blood fat in the body. Like the blood sugar test, the blood fat test also requires fasting for 8-10 hours before the test because food will affect the results.

3.4 Liver function tests

In addition to blood group tests, liver function tests are one of the most commonly ordered birth tests for patients to evaluate liver function or consider liver damage.
When there are symptoms such as unexplained weight loss, alcoholism, or taking medications for liver disease, this test is conducted to monitor liver disease.

4. Other blood tests that require fasting

Basic or comprehensive metabolic tests, including: blood sugar, electrolyte balance, and kidney function tests. Patients are usually asked to fast for 10 to 12 hours before having one of these tests. A blood group test is usually done along with this test. Kidney function indicator kit: to see how well the kidneys are working. Patients are usually asked to fast for 8-12 hours before the test. Vitamin B12 test: to check vitamin B12 levels in the blood. Patients are usually asked to fast for 6-8 hours before the test. In addition, the patient also needs to let the doctor know what medications he is taking because some drugs can affect the test results.

5. What foods and drinks should be avoided before blood test in general, blood group test in particular?

Alcohol affects blood sugar and blood fats, making the results of fasting tests inaccurate. If you are asked to fast before the blood test, alcohol should be avoided. Smoking affects blood test results. If you are asked to fast before the test, you should avoid smoking. Coffee consumption affects digestion and can also affect blood test results. Although it does not affect the blood group test, but because coffee affects digestion and blood collection for testing, so it is not recommended to drink coffee before doing blood tests that require fasting. Gum can speed digestion and may affect results. Avoid chewing gum, even sugar-free ones, and fast for the test. Exercise speeds up digestion and affects results. Therefore, exercise should be avoided during fasting for testing.

To be able to fast safely before taking blood tests as well as blood group tests, the patient may be advised:
Drink plenty of water to ensure enough water needed for the body. Because water does not affect blood test results and is acceptable when fasting. Schedule a time to eat or drink before the test when determining when to do the experiment. Medications can be taken as usual during the fast, unless otherwise directed by your doctor. Pregnant women are often ordered to have a blood group test along with other blood tests to assess the health of the pregnancy, so fasting may be indicated. Fasting to test pregnant women usually does not affect the health of both mother and baby. However, pregnant women should inform their doctor before having the test for instructions on safe fasting before the test. If you miss eating or drinking in the time before the test (due to extreme hunger or confusion), talk to your doctor and reschedule the blood test.

6. Where is the blood group test?

Vinmec Hai Phong International General Hospital is the only hospital in Hai Phong city that owns a very modern Wadiana fully automatic blood grouping machine from Spain, allowing ABO blood grouping techniques to be performed. /Rh (D) on the automaton.
Determination of blood group by this automatic machine allows to minimize possible errors compared to manual methods. In addition, Vinmec Hai Phong's team of doctors and technicians have high professional qualifications, with a strict and strict blood test process, a disciplined environment, and compliance with regulations, helping to ensure absolute safety. correct, accurate of the blood group test. Besides, the team of doctors is always enthusiastic and willing to advise if you have any questions about the test results.

Please dial HOTLINE for more information or register for an appointment HERE. Download MyVinmec app to make appointments faster and to manage your bookings easily.