Coeliac disease (also known as gluten-sensitive enteropathy or coeliac sprue) is a condition of the small intestine. Gluten, a substance found in wheat, barley and rye, reacts with the small bowel, causing damage by activating the immune system to attack the delicate lining of the bowel, which is responsible for absorbing nutrients and vitamins.

The condition is often diagnosed in childhood after weaning when cereals are introduced into the diet, although it can be diagnosed at any age. The symptoms can be subtle, and you may feel unwell for no reason for some time before the diagnosis is made.

If left untreated, coeliac disease can lead to anaemia, bone disease and, rarely, some forms of cancer. The most important treatment is avoiding all food that contains gluten. This usually results in improvement, or even disappearance, of the damage to the lining of the bowel. However, the damage will recur if gluten is re-introduced into the diet.

Coeliac disease has many and varied symptoms, and adult symptoms are different from those of children.

In childhood the symptoms do not appear until gluten-containing foods are introduced into the diet. First symptoms usually include becoming irritable and miserable, with a poor appetite and failure to gain weight. Stools (bowel motions) can become pale, bulky and smell nasty. Some children start with vomiting and diarrhoea, so they are often given the wrong diagnosis of 'gastroenteritis'. The stomach may become swollen, and the muscles of the arms and legs become wasted and thin.

In adults the symptoms may be similar, including weight loss with pale, offensive diarrhoea, or constipation and abdominal bloating with 'wind'. Half of adults with coeliac disease do not have any symptoms from the bowel. They approach their doctor because of extreme tiredness, psychological problems like depression, bone pain and sometimes even fractures (due to thinning of the bones), ulcers in the mouth or a blistering, itchy skin rash mostly on the elbows and knees (called dermatitis herpetiformis).

Some women with coeliac disease have difficulty getting pregnant, and may be diagnosed because of this. Recurrent miscarriage (spontaneous loss of a pregnancy) is sometimes associated with coeliac disease. Some women are diagnosed during pregnancy because their bowel cannot absorb enough iron and vitamins to keep up with the demand of being pregnant, making them severely anaemic. Babies who are small for their age in the womb (intrauterine growth retardation) are more frequently born to mothers with coeliac disease.

There are other rare conditions, which although found in the general population, occur more frequently in people with coeliac disease. These conditions usually require referral to a hospital specialist. They include autoimmune diseases (where the immune system inadvertently attacks the body) such as thyroid disease, insulin-dependent diabetes and a condition that affects the liver called primary biliary cirrhosis.

In one neurology (brain and nerve disease) clinic, several patients who had difficulty walking and coordinating (ataxia) for no apparent reason were tested for coeliac disease in the blood. A significant number of these patients were found to have coeliac disease, although many of them did not have any gut symptoms.