AKT · Gastroenterology/Small bowel & malabsorption

Coeliac disease

Immune-mediated gluten sensitivity → villous atrophy of the small bowel

Overview

An immune-mediated enteropathy triggered by gluten (gliadin) in genetically susceptible people (HLA-DQ2/DQ8), causing villous atrophy and malabsorption. Presents with diarrhoea, bloating, weight loss, iron/folate deficiency anaemia — or silently. Diagnosed by tTG-IgA serology (on a gluten-containing diet) + duodenal biopsy. Lifelong gluten-free diet is the only treatment; associated with dermatitis herpetiformis and hyposplenism.

Recognise

Chronic diarrhoea/steatorrhoea, bloating, abdominal discomfort, weight loss, fatigue; or asymptomatic
Malabsorption: iron-deficiency (or folate) anaemia, osteoporosis, faltering growth in children
Associations: dermatitis herpetiformis (itchy vesicles — see dermatology), type 1 diabetes, autoimmune thyroid, IgA deficiency, hyposplenism; rare enteropathy-associated T-cell lymphoma

Red flags

Refractory symptoms despite a gluten-free diet, or new alarm features → re-evaluate (adherence, refractory coeliac, lymphoma)
Functional hyposplenism → ensure pneumococcal/flu/meningococcal vaccination

Differentials & how to tell them apart

Irritable bowel syndromenormal serology/biopsy; no malabsorption/anaemia/weight loss

Inflammatory bowel diseaseblood/mucus, raised faecal calprotectin/CRP, endoscopic inflammation

Lactose intolerancesymptoms on dairy only; normal coeliac serology

Tropical sprue / giardiasistravel history; specific tests

Investigations

tTG-IgA (+ total IgA) WHILE EATING GLUTEN (the diagnostic serology — false-negative if gluten already excluded); duodenal BIOPSY (villous atrophy, crypt hyperplasia, intraepithelial lymphocytes). FBC/ferritin, B12/folate, calcium/vitamin D; HLA-DQ2/DQ8 (high negative predictive value).

Management

Lifelong gluten-free diet (+ correct deficiencies + hyposplenism vaccines)

1Confirm with tTG-IgA on a gluten-containing diet, then duodenal biopsy. Lifelong gluten-free diet with dietitian support; correct nutritional deficiencies; vaccinate for hyposplenism.Gate: Serology must be taken WHILE the person is still eating gluten (excluding gluten first gives false-negatives); a gastric/duodenal biopsy confirms — don't diagnose on serology alone
2Annual review (serology for adherence, FBC/ferritin, B12/folate, calcium/vitamin D, DXA); investigate non-response (adherence vs refractory coeliac/lymphoma).

Lifelong gluten-free diet — the only effective treatment — dietitian-supported; gluten-free products prescribable (ACBS)

Correct deficiencies + vaccinate — iron/B12/folate/calcium/vitamin D; pneumococcal/flu/meningococcal (hyposplenism)

Key points

Diarrhoea + iron-deficiency anaemia + weight loss = test for coeliac — but only tTG-IgA ON gluten is valid, confirmed by biopsy. Lifelong gluten-free diet. Dermatitis herpetiformis and hyposplenism travel with it.

Monitor & prognosis

Annual serology/bloods/DXA; symptom response.

Excellent on a gluten-free diet; complications if untreated.

Source: NICE NG20; CKS Coeliac disease