What is coeliac disease?|
Coeliac disease or gluten-sensitive enteropathy is a disorder of the small bowel caused by sensitivity to a dietary protein called gluten. Gluten is a component of cereals such as wheat rye and barley .
Cause of coeliac disease
The presence of gluten in the diet is thought to cause damage to the wall of the small bowel resulting in characteristic inflammation and absence of villi. However the thickness of the lining of the gut (mucosa) remains the same (subtotal villus atrophy).
Most of the damage occurs proximal or near end of the small bowel and decreases in severity towards the far end (ileum) , . Villi are finger like projections resulting from folds of the inner layer of the gut wall (mucosa) and are responsible for increasing the surface area of the gut for absorption of digested food material3. Absence of such villi in coeliac disease means that food materials cannot be readily absorbed.
This typically leads to other conditions associated with lack or limited absorption of key nutrients. (especially disorders associated with decreased or lack of absorption of vitamins and minerals)1 . The exact mechanism by which gluten causes damage to the small bowel is unknown but is thought to be due to one or more of the following reasons1,3,4.
- An abnormal immune response to gluten (The body recognises gluten initiates an immune response which damages the wall of the small bowel)
- A deficiency of an enzyme required for breakdown of the protein (peptidase deficiency). The lack of which leads to the accumulation of toxic protein.
- Possible genetic component although the exact method of inheritance is not known. Approximately 10-15% of first-degree relatives will have the condition in affected families.
- Abnormality of the cell of the gut wall (enteryocytes), which allows them to bind gluten.
Symptoms of coeliac disease
The symptoms of coeliac disease can be variable and often non-specific . Failure to thrive and growth failure are two of the common symptoms in children. However both of these are non-specific. The following are some of the other features the patient may present with1,5.
- Diarrhoea - Common in patients especially adults. Often accompanying this is features of steatorrhea (presence of fat in stool). Stools are often bulky, pale and frothy and they float (due to water, electrolyte and fat malabsorption)
- Loss of weight - Some cases anorexia may be present (due to fat and carbohydrate malabsorption)
- Tiredness - Due to iron and folate deficiency and sometimes vitamin B12. Commonly coeliac disease is diagnosed when investigating for possible folate or iron deficiency.
- Skin Rashes - Itchy spots on body surfaces such as knees and elbows
- Abdominal pain - Cramp like abdominal pain or discomfort (due to distension of the small bowel loops)
- Mouth ulcers
- Over long periods, bleeding tendencies and night blindness may be present due to decreased vitamin K and A absorption. Similarly bone and muscle weakness can develop due to decreased vitamin D and calcium absorption
Coeliac disease can appear at any age but is more common in childhood (between 1 and 5 years of age) and between ages of 30 and 501,4. The incidence of coeliac disease varies. Highest recorded is in Ireland (1/300). In the UK incidence is 1 in every 2000.
The disease is uncommon in Japanese and black Africans1. In the UK there is evidence that the incidence of coeliac disease in children is decreasing due to availability of gluten-free foods1.
There are a number of diagnostic tests that can be carried out for coeliac disease. These are outlined below1,4,6.
- Biopsy - Primary method of diagnosis is by taking a biopsy (sample of tissue) from the small bowel.<