What is coeliac disease?
Coeliac disease (spelled celiac in American English) is a chronic autoimmune disorder triggered by gluten — a protein found in wheat, barley and rye. In people with coeliac disease, consuming gluten triggers an immune response that damages the villi — tiny finger-like projections lining the small intestine that absorb nutrients. This causes malabsorption of iron, calcium, folate, vitamin D and fat-soluble vitamins. Coeliac disease affects approximately 1% of the global population but is significantly underdiagnosed — for every diagnosed case, there may be 5–10 undiagnosed cases.
Blood tests for coeliac disease
| Test | Normal | What elevation means |
|---|---|---|
| Anti-tTG IgA (tissue transglutaminase) | Negative / <4 U/mL | Primary screening test; >10x upper limit highly diagnostic |
| Anti-EMA IgA (endomysial antibodies) | Negative | Highly specific; rarely positive without coeliac |
| Total IgA | Normal | Must be checked — IgA deficiency causes false-negative tTG |
| Anti-DGP IgG (deamidated gliadin peptide) | Negative | Used if IgA deficient |
| HLA-DQ2 / DQ8 gene test | — | 95% of coeliac patients carry one of these; negative result rules out coeliac |
Important: you MUST be eating gluten-containing foods for at least 6 weeks before coeliac blood tests (and biopsy). A gluten-free diet before testing causes false-negative results.
Symptoms of coeliac disease
Classic GI symptoms
- Chronic diarrhoea or loose stools
- Abdominal bloating and pain after eating
- Nausea and vomiting
- Weight loss
- Steatorrhoea (pale, fatty, foul-smelling stools that float)
Non-classic and 'silent' coeliac disease
- Iron deficiency anaemia that fails to respond to oral iron supplements
- Fatigue and brain fog
- Short stature in children
- Delayed puberty
- Bone pain (osteoporosis from calcium/vitamin D malabsorption)
- Infertility and recurrent miscarriage
- Peripheral neuropathy (tingling in hands/feet)
- Dermatitis herpetiformis — itchy, blistering skin rash on elbows, knees, buttocks
Nutritional deficiencies common in coeliac disease
| Nutrient | Consequence | Test |
|---|---|---|
| Iron | Iron deficiency anaemia | Ferritin, serum iron, CBC |
| Vitamin D | Osteopenia, bone pain | 25-OH vitamin D |
| Calcium | Osteoporosis | Calcium, DEXA scan |
| Folate (vitamin B9) | Megaloblastic anaemia | Serum folate |
| Vitamin B12 | Neuropathy, anaemia | Serum B12 |
Treatment: strict lifelong gluten-free diet
The only treatment for coeliac disease is a strict, lifelong gluten-free diet. This means avoiding all foods containing wheat (including spelt, kamut, durum, semolina), barley and rye. Oats are controversial — pure uncontaminated oats are tolerated by most coeliacs but avoid initially. With strict adherence, the intestinal villi heal over 1–2 years, nutrients are absorbed again, and symptoms resolve. Anti-tTG antibodies are used to monitor compliance — they should fall to negative within 6–12 months on a gluten-free diet.
Questions to ask your doctor
- Are my tTG and EMA antibodies positive?
- Do I have an IgA deficiency that could cause false-negative results?
- Should I have a duodenal biopsy to confirm?
- What nutritional deficiencies do I have?
- Should I have a DEXA scan for osteoporosis?