Do I need to fast to check for food allergy?

In fact, there is no unified standard answer. Most routine examinations do not require fasting. Only a few special examinations require starvation in advance. Don't go hungry for a long time and suffer in vain.

Two weeks ago, I met a mother who brought her 5-year-old baby for a checkup. She was not allowed to eat at 8 o'clock the night before. In the morning, the baby was crying and holding half a bun at the door of the clinic. I asked if she was afraid that the allergy test would be inaccurate. As a result, the nurse prescribed a routine serum IgE test and asked her to eat the bun first. She had been hungry for almost 12 hours, and the baby was very aggrieved.

The reason why everyone has different opinions on whether to fast is actually the same as the misunderstanding that "all blood draws require fasting". It's like killing everyone with one stone. The items to check for food allergies are different, and the requirements are naturally far different.

The most commonly prescribed blood test to test food-specific IgE is essentially to measure the antibody concentration in the blood. What you eat will not affect the value of this indicator at all. Let alone eating light porridge and noodles, it doesn’t matter if you just drank a cup of milk tea. As long as you don’t take other tests such as liver function and blood lipids that require fasting at the same time, you don’t need to go hungry to take this blood. There is also a commonly done skin prick test, which is to put extracts of various foods on the forearm to see the redness and swelling reaction. This has nothing to do with eating. The only thing to pay attention to is not to take anti-allergic drugs or apply ointments with hormones 3-7 days before the test. I met a young man before who had just eaten a double layer He ordered a beef burger to do some pricking, but the beef extract part turned out to be particularly red. He was still confused, saying that it didn't feel any better just after eating it. Later he realized that every time he ate beef, he would get sporadic urticaria the next day. The reason had never been found before, and it had nothing to do with whether he ate or not.

Of course, not all cases do not require fasting. If the doctor prescribes an oral food challenge test for you, you will really be hungry. This test is the gold standard for diagnosing food allergy. Eat the food you are suspected of allergic to from less to more and observe whether there is any allergic reaction. If there are other foods in the stomach, firstly, it may mask a mild allergic reaction. Secondly, in case of real allergy and vomiting, it will be easier to have more food in the stomach. When it comes to choking, most doctors will repeatedly instruct him several days in advance not to eat eight hours in advance. There was a college student who did a peanut challenge test before and secretly stuffed half a soda cracker before going out because he was afraid of hunger. When he asked about it, he was told to change it to next week. He ran more than 20 kilometers in vain.

If you are really not sure, just ask the doctor during the examination, so as not to suffer the consequences of starving for a long time, or eating in vain. If you really need to fast, don't carry it for too long. Carry some snacks in your pocket, and you can have a few bites right after the examination. Don't be like the little kid before, who was so hungry that he didn't even want to eat his favorite strawberry beans.