What Is a Blood Test? A blood test is when a sample of blood is taken from the body to be tested in a lab. Doctors order blood tests to check things such as the levels of glucose, hemoglobin, or white blood cells. This can help them find problems like a disease or medical condition. Sometimes, blood tests can help them see how well an organ (such as the liver or kidneys) is working. What Is a Tissue Transglutaminase IgA (tTG-IgA) Test? A tissue transglutaminase IgA (tTg-IgA) test is used to help doctors diagnose celiac disease. Celiac disease is an autoimmune disorder in which the immune system mistakenly thinks that gluten — a protein in wheat, barley, rye, and oats — is a foreign invader. The immune system makes antibodies that attack an enzyme in the intestines called tissue transglutaminase (tTG). Why Are tTG-IgA Tests Done? A tTG-IgA test may be done if a child has symptoms of celiac disease, such as poor growth, belly pain, constipation, vomiting, diarrhea, or rashes. A tTg-IgA test also might be done if a child has a condition that makes celiac disease more likely (such as type 1 diabetes), thyroid disease, or a family member with celiac disease. How Should We Prepare for a tTG-IgA Test? For the test to be accurate, your child should be on a gluten-containing diet until the test is done. Your child should be able to eat and drink normally unless also getting other tests that require fasting beforehand. Tell your doctor about any medicines your child takes because some drugs might affect the test results. Wearing a T-shirt or short-sleeved shirt for the test can make things easier for your child, and you also can bring along a toy or book as a distraction. How Is a tTG-IgA Test Done? Most blood tests take a small amount of blood from a vein. To do that, a health professional will: clean the skin put an elastic band (tourniquet) above the area to get the veins to swell with blood insert a needle into a vein (usually in the arm inside of the elbow or on the back of the hand) pull the blood sample into a vial or syringe take off the elastic band and remove the needle from the vein Collecting a sample of blood is only temporarily uncomfortable and can feel like a quick pinprick. Can I Stay With My Child During a tTG-IgA Test? Parents usually can stay with their child during a blood test. Encourage your child to relax and stay still because tensing muscles can make it harder to draw blood. Your child might want to look away when the needle is inserted and the blood is collected. Help your child to relax by taking slow deep breaths or singing a favorite song. How Long Does a tTG-IgA Test Take? Most blood tests take just a few minutes. Occasionally, it can be hard to find a vein, so the health professional may need to try more than once. What Happens After a tTG-IgA Test? The health professional will remove the elastic band and the needle and cover the area with cotton or a bandage to stop the bleeding. Afterward, there may be some mild bruising, which should go away in a few days. When Are tTG-IgA Test Results Ready? Blood samples are processed by a machine, and it may take a few days for the results to be available. If the test results show signs of a problem, the doctor might order other tests to figure out what the problem is and how to treat it. Are There Any Risks From tTG-IgA Tests? A tTG-IgA test is a safe procedure with minimal risks. Some kids might feel faint or lightheaded from the test. A few kids and teens have a strong fear of needles. If your child is anxious, talk with the doctor before the test about ways to make the procedure easier. A small bruise or mild soreness around the blood test site is common and can last for a few days. Get medical care if the discomfort gets worse or lasts longer. If you have questions about the tTG-IgA test, speak with your doctor or the health professional doing the blood draw. Back to Articles Related Articles Celiac Disease Kids who have celiac disease, a disorder that makes their bodies react to gluten, can't eat certain kinds of foods. Find out more - including what foods are safe and where to find them. Read More Celiac Disease Factsheet (for Schools) What teachers should know about celiac disease, and how to help students with the digestive disorder succeed in school. Read More Blood Test (Video) These videos show what's involved in getting a blood test and what it's like to be the person taking the blood sample. 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Find out more by reading this article for kids. Read More Getting a Blood Test (Video) A blood test might sound scary, but it usually takes less than a minute. Watch what happens in this video for kids. Read More Note: All information is for educational purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995-2021 KidsHealth®. All rights reserved. Images provided by The Nemours Foundation, iStock, Getty Images, Veer, Shutterstock, and Clipart.com.