Is a gluten allergy the same as coeliac disease?

Understanding Gluten Allergy vs. Celiac Disease

Gluten allergy and celiac disease are distinct conditions with different underlying mechanisms, though both involve adverse reactions to gluten and may present with similar symptoms. 1

Differences Between Gluten-Related Disorders

Celiac Disease

• Definition: A genetically linked autoimmune enteropathy that affects approximately 1% of the population 1
• Mechanism: Autoimmune response where the body's immune system attacks the small intestine when exposed to gluten proteins (gliadin and glutenin) 1, 2
• Diagnosis:
  • Serological testing for IgA anti-tissue transglutaminase (tTG) and IgA endomysial antibodies (EMA) 1, 2
  • Confirmation with duodenal biopsy showing intestinal damage 1
  • Genetic testing for HLA-DQ2 and HLA-DQ8 genes 2, 3
• Treatment: Strict lifelong gluten-free diet 2, 3

Gluten/Wheat Allergy

• Definition: An immune-mediated IgE response to wheat proteins 1
• Mechanism: IgE-mediated immunological response causing mast cell degranulation and release of histamine 1
• Symptoms: Can develop within minutes of exposure and may include:
  • Hives, angioedema
  • Respiratory symptoms (asthma)
  • Gastrointestinal symptoms
  • Potential anaphylaxis in severe cases 1
• Diagnosis:
  • Skin prick tests
  • Food-specific IgE blood tests
  • Elimination diet followed by controlled food challenge 1
• Treatment: Complete avoidance of wheat/gluten-containing foods 4

Non-Celiac Gluten Sensitivity (NCGS)

• Definition: Adverse reaction to gluten without celiac disease or wheat allergy 1, 3
• Prevalence: Affects up to 6% of the population 1
• Mechanism: Not genetically linked; involves activation of innate immune system and inflammatory pathways 1
• Symptoms: Similar to celiac disease but typically less severe 1, 3
• Diagnosis: Diagnosis of exclusion after ruling out celiac disease and wheat allergy 3, 5
• Treatment: Gluten-free diet, though occasional gluten reintroduction may be possible 6

Clinical Presentation Comparison

Feature	Celiac Disease	Wheat/Gluten Allergy	Non-Celiac Gluten Sensitivity
Onset of symptoms	Hours to days	Minutes to hours	Hours to days
Immune mechanism	Autoimmune (T-cell mediated)	IgE-mediated	Innate immune activation
Intestinal damage	Yes	No	No
Genetic component	Strong (HLA-DQ2/DQ8)	Variable	Not established
Duration of diet	Lifelong	Lifelong/may resolve	Variable

Diagnostic Algorithm

1. Initial evaluation:

   • Assess symptoms: GI symptoms (diarrhea, bloating, abdominal pain), extraintestinal manifestations (fatigue, anemia, skin issues)
   • Family history of celiac disease or other autoimmune disorders
   • Important: Testing must be done while patient is on a gluten-containing diet 2, 3

2. First-line testing:

   • Serological testing:
     • Total IgA and IgA anti-tissue transglutaminase (tTG)
     • If IgA deficient: IgG EMA, IgG DGP, or IgG tTG 1

3. Based on results:

   • If positive serology → Refer for intestinal biopsy to confirm celiac disease
   • If negative serology but high clinical suspicion for wheat allergy → Skin prick test or food-specific IgE testing
   • If both negative but symptoms persist → Consider NCGS diagnosis through elimination diet and controlled challenge

Management

• Celiac disease: Strict lifelong gluten-free diet with monitoring for nutritional deficiencies and potential complications 2
• Wheat allergy: Complete avoidance of wheat; emergency medication (epinephrine) for severe reactions 1, 4
• NCGS: Gluten-free diet with potential for occasional reintroduction to assess tolerance 6

Common Pitfalls to Avoid

1. Self-diagnosis and unnecessary dietary restriction: Many people adopt gluten-free diets without proper diagnosis, which can mask celiac disease if testing is done after gluten elimination 3

2. Failure to test for celiac disease before starting a gluten-free diet: Once a gluten-free diet is initiated, serological testing for celiac disease becomes inaccurate 3

3. Confusing food intolerance with allergy: Food intolerances (like NCGS) don't involve the immune system in the same way as true allergies and have different management approaches 1

4. Overlooking nutritional deficiencies: Gluten-free diets can lead to deficiencies in fiber, B vitamins, and minerals if not properly planned 2

In summary, while both conditions involve adverse reactions to gluten, celiac disease is an autoimmune condition affecting the small intestine, while gluten allergy is an IgE-mediated immune response. Proper diagnosis is essential for appropriate management and to prevent unnecessary dietary restrictions.