Celiac Disease

What happens in celiac disease

The small intestine is lined with tiny finger-like projections called villi, which absorb nutrients. In celiac disease, gluten fragments trigger an immune reaction in genetically susceptible people. The immune system produces antibodies against an enzyme called tissue transglutaminase (tTG) and inflames the intestinal lining. Over time, the villi flatten (villous atrophy), so the gut absorbs fewer nutrients.

Almost everyone with celiac disease carries the gene variants HLA-DQ2 or HLA-DQ8. These are common in the population, so having them does not mean you will develop the disease, but not having them makes celiac disease very unlikely.

Symptoms of celiac disease

Digestive symptoms

• chronic diarrhea, or sometimes constipation
• bloating and gas
• abdominal pain
• pale, foul-smelling, greasy stools
• nausea and vomiting
• weight loss

Symptoms outside the gut

Many adults have mainly non-digestive symptoms:

• iron deficiency anemia that does not respond to iron tablets
• fatigue and "brain fog"
• mouth ulcers and damage to tooth enamel
• an itchy, blistering rash, dermatitis herpetiformis, on elbows, knees, buttocks or scalp
• bone thinning (osteoporosis) and fractures
• tingling or numbness in the hands and feet
• abnormal liver tests
• headaches, joint pain, low mood
• delayed periods, fertility problems or repeated miscarriage

In children

• diarrhea, a swollen belly and irritability in toddlers
• poor weight gain or growth (falling off the growth curve)
• delayed puberty
• dental enamel defects

Some people have no symptoms ("silent" celiac disease) but still have intestinal damage.

Who is at higher risk

• first-degree relatives of someone with celiac disease (about 1 in 10)
• type 1 diabetes
• autoimmune thyroid disease and other autoimmune conditions
• Down syndrome, Turner syndrome and Williams syndrome
• IgA deficiency

Celiac disease vs gluten intolerance vs wheat allergy

How celiac disease is diagnosed

Keep eating gluten until testing is complete. Going gluten-free first can make the tests falsely negative. Guidance suggests eating gluten daily (about the equivalent of 1 to 2 slices of bread) for several weeks before testing.

1. Blood test: tissue transglutaminase IgA (tTG-IgA) with total IgA level. If IgA is low, IgG-based tests are used instead.
2. Upper endoscopy with small intestine biopsies: confirms villous atrophy. Several biopsies are taken from the duodenum.
3. In some children with very high antibody levels, specialist guidelines allow diagnosis without biopsy.
4. Genetic testing (HLA-DQ2/DQ8) helps rule out celiac disease in unclear cases or people already on a gluten-free diet.
5. Skin biopsy confirms dermatitis herpetiformis.

After diagnosis, doctors check for iron, folate, B12, vitamin D and calcium deficiencies, and may arrange a bone density scan.

Treatment: the gluten-free diet

There is no medicine that replaces the diet. A strict gluten-free diet allows the intestine to heal, usually within months in children and up to 2 years or more in adults.

Foods to avoid

• Wheat in all forms, including spelt, durum, semolina, farro, kamut and einkorn
• Barley, including malt, malt vinegar and most beer
• Rye
• Many processed foods that contain hidden gluten: soups, sauces, gravies, soy sauce, seasonings, processed meats, candies

Naturally gluten-free foods

Rice, corn, potatoes, quinoa, buckwheat, millet, sorghum, amaranth, fresh meat, fish, eggs, dairy, legumes, nuts, fruits and vegetables.

Oats are naturally gluten-free but are often contaminated. Oats labeled gluten-free are tolerated by most people with celiac disease once their condition is stable.

Practical tips

• In the US, foods labeled "gluten-free" must contain less than 20 parts per million of gluten.
• Watch for cross-contamination: separate toasters, clean surfaces and utensils, and care with shared butter or jam.
• Check medicines, supplements and lip products.
• When eating out, explain clearly that you have celiac disease, not a preference.
• Work with a registered dietitian experienced in celiac disease.

Complications

Untreated or poorly controlled celiac disease can lead to:

• malnutrition and vitamin deficiencies
• anemia
• osteoporosis and fractures
• infertility and pregnancy complications
• lactose intolerance (usually temporary, until the gut heals)
• nerve problems
• rarely, small intestine lymphoma or cancer, a risk that falls with a strict diet

Living with celiac disease and follow-up

Expect follow-up at 3 to 6 months, then yearly, with tTG-IgA levels (which should fall on a gluten-free diet), blood counts and nutrient checks. If symptoms persist, the most common cause is hidden gluten. Others include lactose intolerance, IBS, microscopic colitis and, rarely, refractory celiac disease.

Frequently asked questions

What are the first signs of celiac disease?

Common early signs are diarrhea, bloating, abdominal pain, weight loss and fatigue. In many adults, the first sign is iron deficiency anemia, mouth ulcers, an itchy rash, or abnormal liver tests. Some people have no symptoms.

How do you test for celiac disease?

Start with a tTG-IgA blood test while you are still eating gluten. If it is positive, an upper endoscopy with small intestine biopsies usually confirms the diagnosis. Do not start a gluten-free diet before testing.

Can celiac disease go away?

No. Celiac disease is lifelong. The intestine heals and symptoms resolve on a strict gluten-free diet, but eating gluten again will restart the immune reaction and damage, even if you do not notice symptoms.

Is celiac disease the same as gluten intolerance?

No. Celiac disease is an autoimmune condition that damages the small intestine and can be confirmed with blood tests and biopsy. Non-celiac gluten sensitivity causes symptoms after gluten without intestinal damage or specific antibodies.

What happens if someone with celiac disease eats gluten?

Some people get diarrhea, bloating, pain or fatigue within hours. Others have no symptoms, but the immune system still damages the intestine. Repeated exposure increases the risk of deficiencies, osteoporosis and other complications.