Food allergy hospital testing

When going to the hospital for a food allergy test, no single item can be used as a basis for diagnosis. All test results must be combined with the actual clinical reaction after eating the food. Blindly avoiding foods based on the "plus sign" on the report sheet may lead to the risk of malnutrition.

Not long ago, when I was helping a teacher sort out cases in the allergy department, I met the mother of a 3-year-old child. She clutched three or four food intolerance reports from different institutions. She frowned and said that she had given up eggs, milk, and wheat for half a year, but the eczema on her face still kept recurring, and the growth curve had dropped by two percentiles. After careful questioning, the doctor found out that the baby secretly ate half a piece of birthday cake last month. Nothing happened, but the report showed two plus signs for IgG in eggs and milk, so he never dared to eat it. Finally, I did a routine IgE test and skin pricking, and the baby’s food-related indicators were all negative. The “food allergy” I had been suffering from for half a year was actually eczema caused by dust mite allergy.

Most of the food allergy-related tests that people often go to the hospital to do now are for IgE-mediated acute allergies - the type that causes swollen lips, wheezes, and even breathlessness within half an hour of eating. The two commonly used tests are serum-specific IgE by venous blood test, and skin prick test. The results of skin pricking are quick and can be seen in 15 minutes, and the price is also cheap. However, you should note that you have to stop taking antihistamines for 3-7 days before going, otherwise it will inhibit the skin reaction and make the measurement inaccurate. I met an older brother before who took loratadine for pricking, but there was no reaction at all. It was a waste of time and he had to change the time. There is no need to stop taking the serum-specific IgE, and the results are relatively stable. However, even if the value is high and there is a "plus sign", it only means that you are allergic to the food, but it does not mean that you are actually allergic. Just like many people who have tested positive for dust mite IgE, but don’t sneeze or runny nose after being exposed to it, the same is true for food. Only if you actually have a reaction after eating this food, can this indicator be of reference significance. It must be said here that the handling methods of different doctors are indeed different. Some doctors in grassroots hospitals may directly tell you taboos based on the number of plus signs, but the top three allergists will definitely repeatedly ask you about your actual eating reactions and will not draw conclusions just by looking at the report sheet.

Another thing that everyone often encounters is the "food intolerance test", which tests food-specific IgG. Nowadays, many private medical examination institutions and even some hospitals are promoting it. There are often hundreds of packages and cost thousands of dollars. There is indeed a lot of controversy about this test. The European Academy of Allergy and Clinical Immunology (EAACI) and my country's food allergy guidelines have long made it clear that IgG testing is not recommended to diagnose food allergy. To put it bluntly, an increase in this indicator is mostly a normal immune response after the body comes into contact with food. It means that you have eaten this thing, but it does not mean that you are intolerant to it. However, some gastroenterologists will use it as a reference, especially for patients with recurrent unexplained diarrhea and irritable bowel syndrome. They will use the results to conduct a short-term dietary avoidance + provocation test, which will not directly make you avoid eating for several years. You still need to make this distinction clearly. Don't spend a lot of money to buy a report. In the end, you dare not eat anything, and the gain outweighs the loss.

If the previous tests are all ambiguous and you are really not sure whether you are allergic or not, there is another recognized gold standard: the oral food challenge test. In the hospital, you will be given the food you are suspected of allergic to starting from a very small amount and slowly increasing the amount. The whole process will be monitored by a doctor and emergency equipment will be prepared to observe whether there are any adverse reactions. This result is the most accurate, but the risk is also high. People with severe allergies may suffer from anaphylactic shock while doing it, so only fully qualified allergists will carry out it and will not prescribe it to you casually. There was a girl who suspected that she was allergic to mango, and the IgE test was at a critical level. She was originally going to do a stimulation, but the doctor just touched her lips with mango peel. In less than two minutes, her lips swelled into sausages. The diagnosis was immediately confirmed, and there was no need for further treatment.

To be honest, if you suspect that you have a food allergy, it is best to keep a food diary for a week before going to the hospital. What did you eat on which day and how long did it take for you to have any reactions? The more detailed you are, the better. It is much more useful than going for a full set of tests costing thousands of dollars with nothing. After asking about your medical history, the doctor will most likely ask you to only check a few suspicious things, which can save you a lot of money and not prescribe a bunch of unnecessary tests for you.

To be honest, the matter of food allergy is really "personalized". Some people have very high test indicators, but nothing happens after eating. Some people have negative indicators and get rashes after eating. It is really not something that can be determined by just one test sheet. I have seen too many people with reports with a plus sign, who dare not touch eggs and milk for several years, and end up with anemia, low protein, immunity getting worse and worse, and allergies becoming more serious. It is really unnecessary. Listening to the judgment of professional doctors and combining it with your own actual eating reactions is more reliable than any high-tech test.