Coeliac disease: tests
What is coeliac disease?
Coeliac disease is a condition that affects the small bowel, caused by an abnormal immune response, or sensitivity, to a dietary protein known as gluten. Gluten is found in wheat, rye and barley, and most types of oats. Sensitivity to gluten causes inflammation and damage to the small intestine, and sometimes the damage is so severe that the intestine is unable to absorb essential nutrients, leading to malnutrition.
Coeliac disease can be difficult to diagnose because the symptoms are so variable. It’s important to note that while coeliac disease can be treated with a gluten-free diet, you should not start this special diet before being tested for the condition, because this can alter your test results and make the diagnosis more difficult.
What tests are used to diagnose coeliac disease?
Blood tests
If your doctor suspects you have coeliac disease, blood tests can be ordered to check for certain antibodies. Some of the blood tests your doctor might order include:
- anti-tissue transglutaminase antibodies;
- deamidated gliadin peptide IgA and IgG tests (which replace anti-gliadin antibodies in some laboratories); and
- anti-endomysial antibodies (although this test is not used as often now).
If the blood tests show high levels of antibodies, you will probably be advised to have a biopsy taken of your small intestine to confirm the diagnosis.
There is also a genetic test that can help exclude coeliac disease as a diagnosis. Genetic testing can be performed on a blood sample or a swab from the inside of the cheek (buccal swab).
Biopsy
A biopsy involves taking a small sample of tissue and examining it under a microscope. If you have coeliac disease, there will be evidence of damage to the lining of the small intestine.
To obtain the biopsy, your doctor will perform an endoscopy — a test where an endoscope (a long, thin flexible tube with a camera on the end) is passed down your throat so that your doctor can see inside your stomach and small intestine. A special instrument is passed through the endoscope to take tiny samples of your intestine.
Additional tests
Further blood tests to check for nutritional problems, which can occur in people with coeliac disease, may also be necessary. Your doctor may want to check whether you have a deficiency in iron, folate, vitamin B12, calcium, or vitamin D, and whether you have anaemia.
A lack of vitamin D can cause osteopenia (a condition resulting in soft, fragile bones, also known as rickets in children) and low calcium and vitamin D can cause osteoporosis (a loss of bone density that makes bones weak and more prone to fractures). If you have coeliac disease, your doctor may recommend that you have a special X-ray, known as a bone density test, to check whether your bones have been affected.
Last Reviewed: 03 March 2010
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2. The Coeliac Society [website]. Coeliac disease what is it? (published 2008, June). Available at: http://www.coeliacsociety.com.au/downloads/C1%20-%20Coeliac%20Disease%20Pamphlet.pdf (Accessed 2010, Mar 1)
3. Coeliac disease [revised September 2006]. In: eTG complete [Internet]. Melbourne: Therapeutic Guidelines Limited; 2009 Nov (Accessed 2009 Dec 14.) http://www.tg.org.au/
4. Gastroenterological Society of Australia (GESA) [website]. Coeliac disease (2007, fourth edition). Available at: http://www.gesa.org.au/leaflets/coeliac-disease.cfm (accessed 2010, Mar 1)
