Celiac Disease — Causes, Symptoms, Diagnosis & Gluten-Free Treatment Guide — Symptoms, Causes & Treatment | MyMedicPlus

Celiac disease (also spelled coeliac disease) is a systemic autoimmune disorder triggered by the ingestion of gluten — a protein found in wheat, barley, rye, and (through contamination) oats — in genetically predisposed individuals. The immune response targets the small intestinal mucosa, leading to progressive villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis. This structural damage impairs the absorption of nutrients including iron, folate, calcium, vitamin D, and fat-soluble vitamins, leading to malabsorption and a broad range of gastrointestinal and extraintestinal manifestations. Celiac disease affects approximately 1% of the population globally, though up to 80% of cases remain undiagnosed. It has a strong genetic basis, with HLA-DQ2 (present in 90–95%) and HLA-DQ8 haplotypes being necessary but not sufficient for disease development.

Celiac disease requires three interacting factors: genetic predisposition (HLA-DQ2/DQ8), gluten exposure, and a dysregulated immune response. Tissue transglutaminase (tTG-2) deamidates gliadin peptides, creating immunogenic epitopes that trigger an adaptive immune response in the lamina propria, producing anti-tTG and anti-endomysial antibodies (IgA class). Genetic risk factors: first-degree relatives of people with celiac disease have a 10% lifetime risk. Associated autoimmune conditions increasing risk: type 1 diabetes (celiac co-occurs in 10%), autoimmune thyroid disease (Hashimoto's), Down syndrome (5–12% prevalence), Turner syndrome, selective IgA deficiency, and Williams syndrome. Environmental factors potentially triggering celiac disease in genetically susceptible individuals include early introduction of large amounts of gluten, rotavirus infections, and altered gut microbiome composition.

Classical gastrointestinal presentation (more common in children): chronic diarrhoea or steatorrhoea (pale, greasy, offensive-smelling stools), abdominal pain and bloating, weight loss, failure to thrive, and nausea/vomiting. Non-classical presentation (increasingly recognized in adults): iron-deficiency anaemia (most common presentation in adults — from duodenal iron malabsorption), fatigue, peripheral neuropathy, ataxia, dermatitis herpetiformis (intensely itchy blistering rash on elbows, knees, and buttocks — pathognomonic of celiac disease), osteoporosis (from calcium/vitamin D malabsorption), delayed puberty, infertility and recurrent miscarriage, mouth ulcers (aphthous stomatitis), and elevated liver enzymes. Silent celiac disease has no symptoms but positive serology and histological changes — more common in first-degree relatives identified on screening.

Serology: anti-tissue transglutaminase IgA (anti-tTG IgA) is the recommended first-line test with sensitivity >95% and specificity >95%. Total serum IgA must be measured simultaneously — IgA deficiency (1 in 200) gives false-negative results, requiring IgG-based tests (deamidated gliadin peptide IgG, anti-tTG IgG). Anti-endomysial antibodies (EMA) are highly specific (99%) and used for confirmation. Testing must be performed while the patient is consuming a normal gluten-containing diet — sensitivity drops dramatically on a gluten-free diet. Upper GI endoscopy with 4–6 biopsies from the duodenum and duodenal bulb: histological Marsh classification grades I (lymphocytosis) to III (total villous atrophy) confirms diagnosis. HLA-DQ2/DQ8 typing has high negative predictive value — its absence effectively excludes celiac disease.

A strict lifelong gluten-free diet (GFD) is the only established treatment for celiac disease. This means complete elimination of wheat, barley, rye, and contaminated oats from the diet. Adherence leads to symptom resolution within weeks and histological recovery within 1–2 years in most patients. Certified gluten-free oats (uncontaminated) are tolerated by most celiac patients. Key management includes: consultation with a specialist celiac dietitian for comprehensive dietary education; correction of nutritional deficiencies (iron, folate, vitamin B12, calcium, vitamin D — supplementation as required); bone density assessment (DXA scan) at diagnosis and follow-up; and hepatitis B vaccination (if not immune, as celiac patients have increased infection susceptibility). Annual monitoring includes repeat anti-tTG IgA serology (to assess GFD adherence), full blood count, ferritin, folate, B12, calcium, and vitamin D levels. Refractory celiac disease (failure to respond to strict GFD) is rare and requires specialist evaluation to exclude lymphoma and may require immunosuppressive therapy.

Untreated coeliac disease causes serious multi-organ complications. Persistent villous atrophy leads to severe malabsorption of iron (iron-deficiency anaemia), folate, calcium, vitamin D, and fat-soluble vitamins (A, D, E, K). Vitamin D and calcium malabsorption causes metabolic bone disease — osteoporosis with significantly elevated fracture risk; hip fracture risk is approximately doubled in untreated coeliac disease. Neurological complications of untreated coeliac disease include coeliac gluten ataxia (cerebral and cerebellar atrophy causing progressive ataxia), peripheral neuropathy, and cognitive impairment — some of which may be irreversible by the time diagnosed. Fertility is impaired: undiagnosed coeliac disease causes menstrual irregularity, delayed puberty, infertility, and recurrent miscarriage. In men, hypogonadism and reduced sperm motility have been documented. Enteropathy-associated T-cell lymphoma (EATL) is a rare but serious small bowel lymphoma occurring almost exclusively in untreated or refractory coeliac disease — with a very poor prognosis. Small bowel adenocarcinoma risk is also significantly elevated. Splenic hypofunction (functional hyposplenism) occurs in up to 30% of longstanding untreated cases, increasing susceptibility to encapsulated bacterial infections (Streptococcus pneumoniae, Haemophilus influenzae). Children with untreated coeliac disease suffer failure to thrive, growth retardation, and dental enamel hypoplasia.

For individuals with diagnosed celiac disease, strict gluten-free diet adherence prevents intestinal damage, complications, and nutritional deficiencies. Cross-contamination must be avoided — separate utensils, cutting boards, and toasters; careful reading of food labels; and vigilance when eating out. First-degree relatives (parents, children, siblings) of people with celiac disease should be offered serological screening every 2–3 years or sooner if symptoms develop, given the 10% lifetime risk. Patients with associated autoimmune conditions (type 1 diabetes, thyroid disease) should be screened for celiac disease at diagnosis of the associated condition. Joining celiac disease support organizations provides ongoing educational resources and advocacy. Despite a gluten-free diet appearing preventive, there is no evidence that avoiding gluten prevents celiac disease in genetically susceptible individuals who have not yet developed the condition.

Consult your GP for testing if you have chronic diarrhoea, unexplained iron-deficiency anaemia, persistent fatigue, significant unexplained weight loss, or a first-degree relative with diagnosed celiac disease. Seek urgent assessment if abdominal symptoms are accompanied by rectal bleeding, severe weight loss, or night sweats — to exclude lymphoma or other serious pathology. Patients established on a gluten-free diet who experience persistent or recurring symptoms despite strict adherence should be reviewed by a gastroenterologist to investigate for refractory celiac disease, inadvertent gluten exposure, or associated conditions including microscopic colitis and small intestinal bacterial overgrowth. Women with celiac disease who are planning pregnancy should be reviewed by a gastroenterologist prior to conception, as active untreated celiac disease significantly increases the risk of miscarriage, preterm birth, and low birthweight even in women without classical gastrointestinal symptoms, underlining the importance of strict dietary compliance in reproductive-age women.