Celiac disease is a chronic autoimmune disorder in which eating gluten triggers an immune response that damages the small intestine. Gluten is a protein found in wheat, barley and rye. In people with celiac disease, this immune reaction damages the villi, the tiny hair-like projections lining the small intestine that absorb nutrients, leading to poor absorption of food.
Celiac disease occurs only in people who are genetically predisposed. It is different from two other conditions that can cause similar symptoms. Non-celiac gluten sensitivity may cause discomfort after eating gluten but does not damage the small intestine, while wheat allergy is a food allergy that does not cause the long-term intestinal damage seen in celiac disease.
Celiac disease affects about 1% of people worldwide, or roughly 1 in 100. A significant proportion of people who have it remain undiagnosed. It is also known as celiac sprue or gluten-sensitive enteropathy.
Symptoms vary widely, and some people have no symptoms at all. Digestive symptoms are more common in children, while more than half of adults have symptoms that are not related to digestion.
Digestive symptoms may include:
- Diarrhea
- Bloating and gas
- Abdominal pain
- Nausea and vomiting
- Constipation
- Weight loss
- Fatigue
Symptoms outside the digestive system may include:
- Iron-deficiency anemia
- Loss of bone density (osteoporosis) or softening of the bones
- Dermatitis herpetiformis, an itchy, blistering skin rash
- Mouth ulcers
- Headaches and fatigue
- Numbness and tingling in the hands and feet
- Joint pain
In children, celiac disease can cause failure to thrive in infants, damaged tooth enamel, short stature, delayed puberty, irritability and neurological symptoms. Dermatitis herpetiformis is linked to celiac disease and can occur even without any digestive symptoms.
Causes and Risk Factors
Celiac disease is triggered by eating gluten, but the precise cause is not fully understood, and it results from a combination of genes and gluten exposure. Its onset can sometimes follow surgery, pregnancy, childbirth, a viral infection or severe emotional stress.
Almost everyone with celiac disease carries specific gene variants known as HLA-DQ2 or HLA-DQ8. However, carrying these genes does not mean a person will develop the condition, as a large proportion of the general population carries them without ever developing celiac disease.
Risk factors include:
- A family history of celiac disease; a first-degree relative with the condition has roughly a 1 in 10 chance of having it
- Other autoimmune conditions, such as type 1 diabetes and autoimmune thyroid disease
- Certain genetic conditions, including Down syndrome, Turner syndrome and Williams syndrome
Diagnosis
Celiac disease is diagnosed using medical and family history, physical examination, blood tests and a small-intestine biopsy. It cannot be diagnosed on symptoms alone.
A critical point is that the person must be eating a gluten-containing diet during testing. Starting a gluten-free diet beforehand can make both the blood tests and the biopsy appear normal and lead to a missed diagnosis.
- Blood tests (serology) — the first-line test measures tissue transglutaminase antibodies (tTG-IgA), usually alongside a total IgA level to detect IgA deficiency, which can cause a false-negative result. Other antibody tests may be used in specific situations
- Small-intestine biopsy — samples are taken from the duodenum during upper endoscopy and examined for damage to the villi; this is considered the definitive way to confirm the diagnosis
- Skin biopsy — used if dermatitis herpetiformis is suspected
- Genetic testing — mainly used to rule the condition out, since the absence of the relevant genes makes celiac disease very unlikely; a positive result alone does not confirm it
Routine screening of the general population is not recommended, but people with a close relative who has celiac disease, or with conditions such as type 1 diabetes, should discuss testing with their doctor.
Treatment and Management
The only treatment for celiac disease is a strict, lifelong gluten-free diet, avoiding wheat, barley, rye and their derivatives. This is the consensus across all major medical bodies.
Even trace amounts of gluten, such as crumbs from a shared cutting board or toaster, can damage the intestine, even when they cause no symptoms. Gluten can also be hidden in processed foods, sauces, some medicines and supplements.
Key elements of management include:
- Working with a registered dietitian experienced in celiac disease, to maintain a balanced gluten-free diet and avoid hidden gluten
- Correcting nutritional deficiencies, which may require supplements of iron, folic acid, vitamin B-12, vitamin D, zinc or others
- Regular medical follow-up with blood tests to confirm the response to treatment
- Additional medication in specific cases, such as for dermatitis herpetiformis or severe inflammation
Symptoms often improve soon after gluten is removed. Healing of the intestine typically takes several months in children and can take longer in adults.
Complications
If celiac disease is untreated, it can lead to:
- Malnutrition, and in children slowed growth and short stature
- Bone disease, including osteoporosis in adults
- Infertility and miscarriage, linked to poor absorption of nutrients
- Lactose intolerance from intestinal damage
- A small increased risk of certain cancers, particularly intestinal lymphoma and small-bowel cancer, mainly in people who do not follow a gluten-free diet
- Nervous system problems and liver damage
- An increased likelihood of developing further autoimmune disorders
Some people have persistent symptoms despite a gluten-free diet, most often because of unintentional gluten intake or a coexisting condition. Rarely, the intestine does not heal despite strict adherence, a situation known as refractory celiac disease, which needs specialist care.
Prognosis
The outlook is excellent for people who follow a strict gluten-free diet. For most people, the small intestine heals and much of the damage can be reversed. There is no cure, so management is lifelong, and persistent symptoms usually point to accidental gluten intake or another condition.
When to See a Doctor
Consult a doctor if you have diarrhea or digestive discomfort lasting more than two weeks, or if a child is pale, irritable, failing to grow, or has a swollen abdomen with foul-smelling, bulky stools. If you have a family member with celiac disease, or a risk factor such as type 1 diabetes, ask your doctor about testing. Importantly, do not start a gluten-free diet before being tested, as this can change the results.