Increasingly, diagnoses are being made in asymptomatic persons as a result of increased screening;^[3] the condition is thought to affect between 1 in 1,750 and 1 in 105 people in the United States.^[4] Coeliac disease is caused by a reaction to gliadin, a prolamin (gluten protein) found in wheat, and similar proteins found in the crops of the tribe Triticeae (which includes other common grains such as barley and rye).^[5]

Upon exposure to gliadin, and specifically to three peptides found in prolamins, the enzyme tissue transglutaminase modifies the protein, and the immune system cross-reacts with the small-bowel tissue, causing an inflammatory reaction. That leads to a truncating of the villi lining the small intestine (called villous atrophy). This interferes with the absorption of nutrients because the intestinal villi are responsible for absorption. The only known effective treatment is a lifelong gluten-free diet.^[5] While the disease is caused by a reaction to wheat proteins, it is not the same as wheat allergy.

This condition has several other names, including cœliac disease (with œ ligature), c(o)eliac sprue, nontropical sprue, endemic sprue, and gluten enteropathy. The term coeliac derived from the Greek κοιλιακός (koiliakós, "abdominal") and was introduced in the 19th century in a translation of what is generally regarded as an ancient Greek description of the disease by Aretaeus of Cappadocia.^[6][7]

Signs and symptoms[edit]

Severe coeliac disease leads to the characteristic symptoms of pale, loose and greasy stool (steatorrhoea) and weight loss or failure to gain weight (in young children). People with milder coeliac disease may have symptoms that are much more subtle and occur in other organs than the bowel itself. It is also possible to have coeliac disease without any symptoms whatsoever.^[5] Many adults with subtle disease only have fatigue or anaemia.^[3]

Gastrointestinal[edit]

The diarrhoea that is characteristic of coeliac disease is (chronic) pale, voluminous and abnormally malodorous. Abdominal pain and cramping, bloatedness with abdominal distension (thought to be due to fermentative production of bowel gas) and mouth ulcers^[8] may be present. As the bowel becomes more damaged, a degree of lactose intolerance may develop.^[5] Frequently, the symptoms are ascribed to irritable bowel syndrome (IBS), only later to be recognised as coeliac disease; a small proportion of people with symptoms of IBS have underlying coeliac disease, and screening for coeliac disease is recommended for those with IBS symptoms.^[9]

Coeliac disease leads to an increased risk of both adenocarcinoma (small intestine cancer) and lymphoma of the small bowel (enteropathy-associated T-cell lymphoma or EATL). This risk returns to baseline with diet. Long-standing and untreated disease may lead to other complications, such as ulcerative jejunitis (ulcer formation of the small bowel) and stricturing (narrowing as a result of scarring with obstruction of the bowel).^[10]

Malabsorption-related[edit]

The changes in the bowel make it less able to absorb nutrients, minerals and the fat-soluble vitamins A, D, E, and K.^[5][11]

• The inability to absorb carbohydrates and fats may cause weight loss (or failure to thrive/stunted growth in children) and fatigue or lack of energy.
• Anaemia may develop in several ways: iron malabsorption may cause iron deficiency anaemia, and folic acid and vitamin B₁₂ malabsorption may give rise to megaloblastic anaemia.
• Calcium and vitamin D malabsorption (and compensatory secondary hyperparathyroidism) may cause osteopenia (decreased mineral content of the bone) or osteoporosis (bone weakening and risk of fragility fractures).
• A small proportion have abnormal coagulation due to vitamin K deficiency and are slightly at risk for abnormal bleeding.
• Coeliac disease is also associated with bacterial overgrowth of the small intestine, which can worsen malabsorption or cause malabsorption despite adherence to treatment.^[12]