Coeliac disease: four out of five are undiagnosed

Coeliac disease affects about one person in 100, although four out of five who have the condition don’t know they have it. So what is coeliac disease? What causes it? And how is it diagnosed and treated?

Coeliac disease is a permanent intestinal intolerance to dietary gluten, which causes damage to the cells of the small bowel (small intestine). Gluten is a particular type of protein found in certain common grains, like wheat. The intolerance causes a flattening of the tiny, finger-like projections called villi, which line the inside of the bowel. If undiagnosed, the condition can cause long term poor health and other less common effects such as:

• osteoporosis due to reduced dietary calcium absorption
• infertility
• miscarriages
• depression
• dental enamel defects 
• increased risk of gastrointestinal and cancer of the oesophagus.

It is important to see your doctor if you suspect you may have the condition.

Symptoms of coeliac disease

Symptoms of coeliac disease are many and varied. They can be similar to those of several other conditions, so diagnosis is not easy:

In adults, common symptoms include:

• Diarrhoea - this may begin at any age and is often present for years prior to diagnosis. It may first appear after other illnesses (eg. gastroenteritis) or abdominal operations 
• Fatigue, weakness and lethargy
• Anaemia - iron or folic acid deficiency are the most common. The anaemia will either not respond to treatment or will recur after treatment until the correct diagnosis is made and a gluten free diet is begun
• Weight loss 
• Constipation - some are more likely to experience constipation rather than diarrhoea
• Flatulence and abdominal distension 
• Cramping and bloating 
• Nausea and vomiting. 
  

Less commonly, adults may experience:

• Easy bruising of the skin
• Ulcerations and/or swelling of mouth and tongue 
• Miscarriages and infertility 
• Low blood calcium levels with muscle spasms 
• B12, A, D, E and K vitamin deficiency 
• Skin rashes such as dermatitis herpetiformis
• Altered mental alertness 
• Bone and joint pains.

In children, symptoms do not appear until gluten-containing foods are introduced into the diet. It is also possible for symptoms to appear later. The common symptoms include:

• Large, bulky, foul stools
• Diarrhoea or constipation
• Poor weight gain
• Weight loss in older children
• Chronic anaemia
• Retarded growth
• Abdominal distention, pain and flatulence
• Nausea and vomiting
• Irritability.

Diagnosing coeliac disease

Since other conditions can closely mimic coeliac disease, a definitive diagnosis can only be made by showing that the bowel lining is damaged. This is done by a specialist gastroenterologist performing a bowel biopsy. A special fibre optic instrument is passed down into the small bowel and a tiny sample of the bowel lining taken for analysis.

Before a bowel biopsy is done, though, a specific panel of blood tests that measures antibodies to gluten are available. This gives is a useful way of identifying who might need a biopsy. It may also help to reduce the incidence of delayed diagnosis.

The Coeliac Society of New Zealand recommends that a gluten-free diet is not started, based on a suspicion of gluten intolerance. Once the gluten-free diet is started, diagnosis becomes much more difficult as it will interfere with establishing the correct diagnosis and may delay the diagnosis of another condition with similar symptoms. Trialling of a gluten-free diet does not provide a diagnosis of coeliac disease. Investigations, such as blood tests and biopsies, taken while on a gluten-free diet, will not pick up on the disease.

The small bowel biopsy will sometimes need repeating, some time after starting a gluten-free diet, to check that the bowel lining is recovering.  For absolute certainty in the diagnosis, it may even be recommended that gluten be reintroduced and a third biopsy performed, to confirm that the recovered small bowel is becoming damaged again with the “gluten challenge”. This final biopsy removes all doubts about the absolute necessity of a lifelong gluten-free diet.

It is important to discuss the possibility of coeliac disease with a doctor, if anyone has a close relative with the condition or if they have been treated for anaemia on previous occasions.

The cause of coeliac disease

Coeliac disease occurs in family groups and is probably genetic. Around 10% of all first degree relatives (parents, brothers, sisters or children) of known coeliacs also have the disease. If one identical twin is affected, the other twin is virtually certain to be affected. Environmental factors, such as water quality and minerals in the local soil, are also thought to play a part.

Treatment or cure?

There is no known cure for coeliac disease, but treatment with a gluten-free diet will allow most people to return to normal health.

A gluten-free diet means a lifelong, no-exceptions diet, leaving out all foods containing wheat, rye, barley, triticale and sometimes oats.

Older people may take longer to recover once they have adopted this diet. Sometimes lost nutrients such as iron, folic acid and some vitamins may need to be replaced at the start of treatment. In addition it is sometimes beneficial to reduce cow’s milk in the diet at first, to allow the bowel to replenish its levels of the enzyme lactase that aids its digestion.

Coeliacs remain sensitive to gluten throughout their life. If gluten remains in the diet, damage to the small bowel can still be happening, even if symptoms disappear.

So what’s going on in there?

Coeliacs are sensitive to gluten (the protein found in wheat, rye, barley triticale and oats), which reacts with the small bowel lining, damaging it and causing loss of effective absorption surface area of thefinger-like projections called villi.

Cells on normal villi break down and absorb nutrients in food. In coeliac disease, these cells become flat and inflamed and the surface area, which enables the absorption of nutrients and minerals from food, is seriously depleted. This poor absorption leads to deficiencies in vitamins, iron, folic acid and calcium. Sugars, proteins and fats are often poorly absorbed as well. 

If you are concerned about coeliac disease, see your doctor, who will be able to assess the risk and arrange for screening tests.

More information about coeliac disease and the gluten-free diet can be obtained from the Coeliac Society of New Zealand.

Information provided by the Coeliac Society of New Zealand. Edited by everybody, May 2009.