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Celiac Disease

Immune-mediated enteropathy triggered by gluten in genetically susceptible patients, causing villous atrophy, malabsorption, iron deficiency anemia, and dermatitis herpetiformis

Review date
reviewed 2026-05-04
Reading time
8 min read
Author
Dr Kola Tytler MBBS CertHE MBA MSt MRCGP
Gastroenterology & Hepatologycommonlong-term-condition
On this page
Condition details
Gastroenterology & Hepatology
common
8 min read
reviewed 2026-05-04
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About This Page

This is a clinician-written, evidence-based summary aligned to the USMLE Step 2 CK Content Outline. It is intended for medical students preparing for USMLE Step 2 CK. Management reflects current ACC/AHA, USPSTF, and APA guidelines. Always cross-reference with UpToDate, institutional protocols, and clinical judgment.

Key points

  • Best initial test: tissue transglutaminase IgA plus total IgA while patient is eating gluten
  • Confirm most adult diagnoses with EGD and multiple duodenal biopsies
  • Treatment is lifelong strict gluten-free diet and correction of nutrient deficiencies
  • Dermatitis herpetiformis = pruritic grouped vesicles on extensor surfaces
  • Do not start gluten-free diet before testing unless medically necessary

Overview

Celiac disease is autoimmune small intestinal enteropathy caused by gluten exposure in genetically susceptible patients, usually HLA-DQ2 or HLA-DQ8. Gluten triggers tTG autoantibodies, intraepithelial lymphocytosis, crypt hyperplasia, and villous atrophy.

Epidemiology

Celiac affects about 1% of the population and is more common in type 1 diabetes, autoimmune thyroid disease, Down syndrome, Turner syndrome, IgA deficiency, and first-degree relatives. Many patients present without classic diarrhea.

Clinical Features

Symptoms
Chronic diarrhea, steatorrhea, bloating, flatulence, weight loss
Iron deficiency anemia refractory to oral iron
Fatigue, aphthous ulcers, infertility, osteoporosis
Dermatitis herpetiformis on extensor surfaces
Severe dehydration, electrolyte derangement, or profound weight loss
Signs
Pallor, glossitis, angular cheilitis
Low BMI or muscle wasting
Excoriated papulovesicular rash on extensor surfaces
Signs of vitamin deficiency

Investigations

First-line
tTG-IgA plus total IgABest initial screen; total IgA identifies selective IgA deficiency
DGP-IgG or tTG-IgGUse if IgA deficient
CBC, ferritin, folate, B12, vitamin D, calcium, LFTsAssess malabsorption
Second-line
EGD with duodenal biopsiesConfirms diagnosis in most adults; villous atrophy and crypt hyperplasia
HLA-DQ2/DQ8High negative predictive value when diagnosis uncertain
Specialist
Skin biopsy with direct immunofluorescenceDermatitis herpetiformis shows granular IgA deposition
Dietitian assessmentHidden gluten exposure and nutritional adequacy

Management

ACG Guideline: Celiac Disease 2023
1
Before diagnosis
  • Do not start gluten-free diet before testing
  • If already gluten-free, consider HLA testing and supervised gluten challenge
2
Treatment
  • Lifelong strict gluten-free diet avoiding wheat, barley, rye
  • Replace iron, folate, B12, vitamin D, calcium as needed
  • Monitor symptoms and tTG levels
3
Refractory symptoms
  • Check hidden gluten exposure first
  • Evaluate IBS, microscopic colitis, lactose intolerance, pancreatic insufficiency, SIBO, IBD
  • Specialist evaluation for refractory celiac and lymphoma risk

Complications

  • Nutrient deficiencies: Iron, folate, B12, vitamin D, calcium.
  • Osteoporosis: Calcium and vitamin D malabsorption.
  • Infertility: Improves with treatment.
  • Enteropathy-associated T-cell lymphoma: Rare but serious.
USMLE Step 2 CK Exam Tips
  • 1Test while eating gluten
  • 2Best initial test = tTG-IgA plus total IgA
  • 3IgA deficiency causes false-negative tTG-IgA
  • 4Iron deficiency may be the only clue
  • 5Dermatitis herpetiformis = celiac disease
  • 6Duodenal biopsy shows villous atrophy, crypt hyperplasia, intraepithelial lymphocytes
  • 7No improvement: hidden gluten exposure is most common

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regional clinical guidance

Celiac Disease: guidance by region

Recommendations, thresholds and pathways can differ. Open the page written for the jurisdiction you need.

United StatesCeliac diseaseDigestive · reviewed 2026-08-20

Verified Sources & References

ACG Guideline: Celiac Disease 2023
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