What are the recommended investigations and treatment for celiac disease?

Celiac Disease Investigation and Treatment

Screen with IgA tissue transglutaminase (IgA-TG2) antibodies and confirm diagnosis with duodenal biopsy showing villous atrophy in adults, followed by lifelong strict gluten-free diet as the only proven treatment. 1, 2

Diagnostic Approach

Initial Serological Testing

• First-line test: IgA tissue transglutaminase (IgA-TG2) antibodies using validated high-performance ELISA 3
• Simultaneously check total IgA to identify IgA deficiency (present in ~2-3% of celiac patients)
• If IgA deficient: Use IgG-based tests (IgG deamidated gliadin peptide or IgG-TG2) 2, 4
• Critical: Patient must be on a gluten-containing diet during testing 2, 5

Duodenal Biopsy Confirmation

Biopsy remains essential for diagnosis in adults with rare exceptions 2

Biopsy protocol:

• Take ≥4 biopsies from the second part of duodenum (distal duodenum) 2, 3
• Include biopsies from duodenal bulb to maximize diagnostic yield 1, 2
• Look for: villous atrophy, crypt hyperplasia, and intraepithelial lymphocytosis (≥25 IELs/100 enterocytes) 2

Diagnostic criteria:

• Definite celiac disease: Villous atrophy (Marsh 3) + positive serology 2
• Probable celiac disease: ≥25 IELs without villous atrophy + positive serology 2

No-Biopsy Approach (Conditional)

The 2025 ESsCD guidelines introduced a conditional no-biopsy approach for highly selected adults:

• IgA-TG2 ≥10× upper limit of normal (ULN)
• High-performance validated ELISA used
• Symptomatic patient
• This remains controversial and not universally adopted 3

Important caveat: Biopsy is still preferred in adults because alternative serious diagnoses (lymphoma, Crohn's disease, other causes of villous atrophy) are more common than in children, and not all commercial IgA-TG2 kits are high quality 2

HLA Testing (Second-Line Only)

• HLA-DQ2/DQ8 typing has high negative predictive value but should be reserved for unclear cases 1
• Use when: inconclusive antibodies, equivocal histology, patient already on gluten-free diet, or diagnostic uncertainty 1, 5
• Not recommended as first-line screening 1

Treatment

Gluten-Free Diet (GFD)

A lifelong strict gluten-free diet is the only proven effective treatment 2, 6

Treatment goals:

• Relieve symptoms
• Achieve mucosal healing
• Prevent complications (osteoporosis, malabsorption, anemia, lymphoma)
• Maintain good quality of life 2

Implementation requires:

• Expert dietitian involvement - essential for success 2
• Education on hidden gluten sources, cross-contamination, food labeling 4
• Nutritional counseling to prevent vitamin/mineral deficiencies (iron, calcium, vitamin D, B vitamins) 1
• Support groups and resources 4

Follow-Up Strategy

Recommended schedule: Every 12 months 1

At each visit assess:

• Symptom resolution
• Dietary adherence (dietary review + repeat serology)
• Nutritional status and deficiencies
• Growth parameters in children/adolescents 1

Follow-up biopsy: No consensus exists 2

• Some experts recommend routine biopsy at 2-5 years on GFD
• Others reserve for: persistent/recurrent symptoms, non-responsive disease, or diagnostic uncertainty 2

Non-Responsive Celiac Disease

20% of adults have therapy-resistant disease 1

Systematic workup required:

1. Confirm original diagnosis - review serology and histology
2. Assess dietary adherence - most common cause is unintentional gluten contamination 6, 4
3. Check for coexisting conditions: lactose intolerance, microscopic colitis, small intestinal bacterial overgrowth, pancreatic insufficiency 4, 5
4. Repeat duodenal biopsy to evaluate mucosal healing and exclude complications 2
5. Rule out refractory celiac disease (rare, poor prognosis) or enteropathy-associated T-cell lymphoma 6, 5

Novel Therapies (Investigational Only)

Multiple agents are in clinical trials but none are approved for clinical use 2, 5:

• Prolyl endopeptidases (gluten-degrading enzymes)
• Larazotide acetate (tight junction regulator)
• TG2 inhibitors
• Immunomodulatory approaches

These remain experimental and should not replace GFD 2

Key Pitfalls to Avoid

1. Testing patients already on gluten-free diet - causes false negatives; requires gluten challenge (controversial and often poorly tolerated) 2, 5
2. Relying on serology alone in adults - biopsy confirmation prevents misdiagnosis of serious alternative conditions 2
3. Inadequate biopsy sampling - <4 biopsies or missing duodenal bulb reduces diagnostic sensitivity 2, 3
4. Poor follow-up - only 35% of patients maintain regular follow-up, leading to non-adherence and complications 1
5. Assuming non-responsiveness is refractory disease - dietary gluten contamination is the most common cause 6, 4