What is Celiac Disease?
 

Celiac Disease is a chronic autoimmune disorder triggered by eating gluten—a protein found in wheat, barley, rye, and triticale.

Unlike a food allergy (such as a wheat allergy) or non-celiac gluten sensitivity, celiac disease involves a destructive immune response. When a person with celiac disease eats gluten, their immune system produces autoantibodies that attack and flatten the villi—tiny, finger-like projections lining the small intestine. Because villi are responsible for absorbing nutrients, their destruction leads to malabsorption, nutritional deficiencies, and systemic health issues.

Pathophysiology & Genetics
 

• Autoimmune Mechanism: Ingestion of gluten leads to its breakdown into gliadin peptides. In genetically susceptible individuals, tissue transglutaminase (tTG) enzymes modify gliadin, triggering an immune cascade that releases autoantibodies (like anti-tTG IgA) and causes intraepithelial lymphocytic infiltration and villous atrophy.

• Genetic Predisposition: Nearly all individuals with celiac disease carry specific human leukocyte antigen (HLA) gene variants:

  • HLA-DQ2 or HLA-DQ8

  • Note: Having these genes is necessary to develop celiac disease, but carrying them does not guarantee disease development (they are present in ~30% of the general population, but only ~1% develop the disease).

Signs & Symptoms
 

Gastrointestinal Symptoms

• Chronic diarrhea or bulky, foul-smelling, fatty stools (steatorrhea)

• Persistent abdominal pain, bloating, and excess gas

• Nausea, vomiting, and constipation (especially in pediatric patients)

• Unintended weight loss or failure to thrive / growth delay in children

Other Manifestations

• Dermatitis Herpetiformis: A severe, itchy, blistering skin rash typically found symmetrically on the elbows, knees, buttocks, or scalp.

• Hematologic: Iron-deficiency anemia often refractory to oral iron supplementation, caused by impaired absorption in the duodenum.

• Musculoskeletal: Early-onset osteopenia, osteoporosis, or joint pain due to impaired calcium and vitamin D absorption.

• Neurologic: Peripheral neuropathy (tingling/numbness in hands and feet), ataxia, or chronic headaches.

• Other: Chronic fatigue, elevated liver enzymes, mouth ulcers (aphthous stomatitis), and reproductive issues (unexplained infertility or recurrent miscarriages).

Diagnostic Workup (The "Stay on Gluten" Rule)
 

 

Crucial Diagnostic Warning: Patients must continue eating a gluten-containing diet throughout the diagnostic process. Removing gluten before testing can cause antibody levels to drop and intestinal villi to heal, leading to false-negative test results.

Serological Blood Testing

• Anti-Tissue Transglutaminase IgA (tTG-IgA): The single best initial screening test with high sensitivity and specificity.

• Total Serum IgA: Measured concurrently to rule out selective IgA deficiency, which can cause false-negative IgA-based tests. (If IgA deficient, IgG-based tests like IgG-tTG or IgG-DGP are used).

• Anti-Endomysial Antibody (EMA-IgA): Highly specific confirmatory blood test.

Upper Endoscopy (EGD) with Duodenal Biopsies

• Considered the gold standard for confirming diagnosis in adults.

• A gastroenterologist collects multiple tissue samples from the bulb and second/third portions of the duodenum to assess for villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes (evaluated via the Marsh classification scale).

Genetic Testing (HLA-DQ2 / HLA-DQ8)

• Useful primarily for its high negative predictive value. If a patient tests negative for both HLA-DQ2 and HLA-DQ8, celiac disease can be almost entirely ruled out.

Management & Treatment Strategies
 

• Strict, Lifelong Gluten-Free Diet (GFD):

  • The only effective treatment for celiac disease. Eliminating all traces of gluten halts the autoimmune response, allows intestinal villi to heal, and prevents long-term complications.

  • Foods to Strictly Avoid: Wheat, rye, barley, spelt, kamut, triticale, malt (malt extract, malt vinegar), and standard brewer's yeast.

  • Cross-Contamination: Even microscopic amounts of gluten (e.g., shared fryers, shared cutting boards, or toaster crumbs) can trigger intestinal inflammation.

• Nutritional Assessment & Supplementation:

  • Baseline screening for micronutrient deficiencies: Iron/Ferritin, Vitamin D, Vitamin B12, Folate, Zinc, and Calcium.

  • Supplementation as indicated until intestinal absorption capacity recovers.

• Bone Density Evaluation:

  • Baseline DXA scan for adults to screen for osteoporosis or osteopenia due to chronic malabsorption.

• Refractory Celiac Disease:

  • Defined as persistent or recurrent malabsorptive symptoms and villous atrophy despite strict adherence to a gluten-free diet for 12+ months. Requires specialized gastroenterology management to evaluate for secondary complications (such as enteropathy-associated T-cell lymphoma / EATL).