Coeliac disease is a condition caused by an abnormal immune response, or sensitivity, to a dietary protein known as gluten. Gluten is found in wheat, rye and barley.
In people with coeliac disease, sensitivity to gluten causes inflammation and damage to the small bowel, and sometimes the damage is so severe that the intestine is unable to absorb essential nutrients, leading to malnutrition.
What are the symptoms?
The symptoms of coeliac disease vary widely from person to person. Some people may have no symptoms at all, while others complain of tiredness or gastrointestinal symptoms. Some of the more common symptoms include:
- intermittent diarrhoea;
- abdominal pain or cramping;
- bloating; and
- weight loss.
Children with coeliac disease may also have:
- slow growth or weight loss;
- delayed puberty;
- short stature;
- a swollen abdomen; and
- problems with the enamel on their permanent teeth.
Up to three-quarters of people with coeliac disease do not realise that they have the condition, either because they have no symptoms, or their symptoms are non-specific and coeliac disease has not been diagnosed.
What happens to the bowel in people with coeliac disease?
In people with coeliac disease, the small intestine becomes inflamed when foods containing gluten are eaten. This inflammation damages the lining of the small intestine, which has tiny, finger-like projections called villi that are responsible for absorbing nutrients from food. When the villi are damaged, they may flatten out, making it much more difficult for you to absorb nutrients.
How common is coeliac disease?
Coeliac disease affects about one per cent of Australians, and has been diagnosed more frequently in recent years. Many people with coeliac disease do not realise they have it.
What causes coeliac disease?
Coeliac disease is an immune disorder thought to be caused by a combination of genetic and environmental factors.
There are several genes associated with coeliac disease – the most important are called HLA DQ2 and HLA DQ8. Nearly every person with coeliac disease has either or both of these genes. However, many people with these genes do not have coeliac disease, so other factors are also important in the development of coeliac disease.
People of all ages can be affected, but symptoms only appear when gluten is part of the diet. Sometimes a stressful event, such as an infection, injury, or surgery, will trigger symptoms of coeliac disease. There are some factors that can put you at increased risk of developing coeliac disease, including:
- a family history of the disease (if someone in your immediate family is affected, you have about a 10 per cent chance of having coeliac disease);
- being Caucasian; and
- having another genetic condition, such as Down syndrome or Turner syndrome.
Complications and associated conditions
Some people with untreated coeliac disease will have conditions relating to the malabsorption of certain nutrients from the diet.
- A lack of vitamin D can cause osteomalacia — a condition resulting in soft, fragile bones, also known as rickets in children.
- Low calcium and vitamin D can cause osteoporosis — a loss of bone density that makes bones weak and more prone to fractures.
- A lack of iron, folate or vitamin B12 can cause anaemia.
Untreated coeliac disease can also result in an increased risk of:
- difficulty getting pregnant (infertility) in women, and in some cases, miscarriages; and
- lymphoma – a type of cancer – of the small bowel.
Treatment with a gluten-free diet reduces the risk of complications developing.
People with coeliac disease are also more likely to have other medical conditions that are related to problems with the immune system, such as:
- certain types of thyroid disease;
- type 1 diabetes;
- Sjogren’s syndrome;
- rheumatoid arthritis; or
- a skin condition called dermatitis herpetiformis.
How is coeliac disease diagnosed?
Coeliac disease can be difficult to diagnose based on symptoms because they are so variable. Your doctor will ask about your symptoms and whether anyone in your family has similar symptoms or has been diagnosed with coeliac disease. They will also perform a physical examination.
If your doctor suspects you have this condition, they may suggest some tests for coeliac disease, including blood tests which can be ordered to check for certain antibodies that indicate an immune system reaction to gluten.
Antibody tests for coeliac disease 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 commonly used nowadays).
Antibody testing is unreliable if you have removed gluten from your diet before being tested. Discuss your current diet with your doctor before being tested for coeliac disease. You may need to re-introduce gluten into your diet for several weeks (known as a gluten challenge) so that a diagnosis can be made.
Sometimes, gene (HLA) testing is recommended for people who have been eating a gluten-free diet. Gene testing can be done on a blood sample or a sample of cells scraped from the inside of your cheek. Gene tests alone cannot diagnose coeliac disease, but may be helpful in ruling out coeliac disease in people with a negative test.
To confirm a diagnosis of coeliac disease, a biopsy of your small intestine is recommended. 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 sample(s) of your intestine.
Starting a gluten-free diet before being tested for coeliac disease can alter your test results and make the diagnosis more difficult. Make sure you discuss your current diet with your doctor before having a small bowel biopsy.
Further blood tests to check for nutritional deficiencies may also be necessary. Your doctor may want to check whether you have a deficiency in iron, folate, vitamin B12, calcium, or vitamin D.
What is the treatment for coeliac disease?
There is no cure for coeliac disease, but it can be treated with a gluten-free diet.
Most people find that once gluten is excluded from their diet, their symptoms improve dramatically because the inflammation in the small intestine resolves, and any damage to its lining can heal. People with coeliac disease need to stick to the gluten-free diet for the rest of their lives to prevent further inflammation.
Your doctor may recommend you see a dietitian with expertise in coeliac disease, who can advise you on how to exclude gluten from your diet and suggest healthy eating alternatives. You will most likely become an expert in reading food labels and knowing which foods are best avoided.
What are the main foods that people with coeliac disease should avoid?
- Gluten is found in wheat, rye, and barley. Foods made from grains such as bread, pasta, cereals, pastry and biscuits should generally be avoided as they contain gluten. However, it is possible to buy gluten-free alternatives to these foods, which are made from corn, rice, soy or other gluten-free grains.
- There are also other food ingredients and food additives that may contain gluten, such as malt flavouring, some food preservatives and stabilizers and modified food starch — your dietitian can advise you on what to look for on food labels.
- Oats can be a problem for people with coeliac disease. Most people with coeliac disease can eat a small amount of oats, providing the oats have not been contaminated with wheat gluten during growing or processing. Oats that have been labelled as gluten free are the best choice. Your dietitian will be able to advise you on whether you should eat oats.
Other sources of gluten
There are some medicines and vitamin supplements that contain gluten, so you will need to check with your doctor or pharmacist before taking any new medicines.
Gluten may also be found in other products that can sometimes be ingested. These products may include some types of make-up (cosmetics), lip balm, toothpaste, mouthwash, skin products and glue on stamps and envelopes. Carers of children with coeliac disease should be aware that modelling dough can contain gluten.
Ingesting even small amounts of gluten can cause inflammation in the small intestine and increase the risk of complications developing, even if you don’t experience symptoms.
Medicines and supplements
A small number of people who have severely damaged small intestines don’t improve straight away with a gluten-free diet. These people may need medicines, such as corticosteroids, to help reduce the inflammation.
Some people may also need vitamin and mineral supplements to treat nutritional deficiencies.
Screening for family members
Because coeliac disease runs in families, if one of your immediate family members has been diagnosed, it’s recommended that you see your doctor for advice on being tested for coeliac disease.
Coeliac disease support groups
There is support and information available for people with coeliac disease from organisations such as Coeliac Australia. You may find it helpful talking to other people with coeliac disease, who may be able to provide food and recipe ideas and advice on living with this ongoing condition.
Gluten-free food options are more widely available these days as there are increased numbers of people wishing to remove gluten from their diets. However, there is often still a lack of understanding and awareness about coeliac disease, and the fact that a gluten-free diet is not simply a lifestyle choice for those with coeliac disease. Talking with other people affected by coeliac disease may help alleviate frustrations and help you develop ways to cope with your condition.
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3. Gastroenterological Society of Australia (GESA); Digestive Health Foundation (DHF). Coeliac disease (updated Feb 2012). http://www.gesa.org.au/consumer.asp?id=45 (accessed May 2016).
4. Coeliac disease (published March 2016). In: eTG complete. Melbourne: Therapeutic Guidelines Limited; 2016 Mar. http://online.tg.org.au/complete/ (accessed May 2016).