Celiac disease

A 34-year-old female presents with a 6-month history of chronic diarrhea, bloating, intermittent abdominal pain, and unintentional weight loss. She describes her stools as loose, foul-smelling, and difficult to flush, suggestive of steatorrhea. She also reports fatigue and generalized weakness and has a known history of iron deficiency anemia for which she is taking supplements. Recently, she developed a pruritic vesicular rash over her elbows and knees consistent with dermatitis herpetiformis. On evaluation, her BMI is 21 kg/m². Laboratory investigations reveal microcytic anemia with iron studies showing decreased ferritin, increased TIBC, low serum iron, and reduced transferrin saturation. Serologic testing is positive for anti-tTG (IgA), anti-endomysial, and anti-deamidated gliadin antibodies. Small bowel biopsy demonstrates villous atrophy, intraepithelial lymphocytosis, and crypt hyperplasia, and the D-xylose test shows decreased absorption. These findings are consistent with a diagnosis of celiac disease. Diagnosis?

Diagnosis is Celiac disease.

1. Definition

Celiac disease is a chronic autoimmune disorder triggered by dietary gluten, resulting in immune-mediated inflammation and damage of the small intestinal mucosa, leading to malabsorption and systemic manifestations.

2. Etiology / Associations

1. Triggered by gluten (wheat, barley, rye)
2. Strong association with HLA-DQ2 and HLA-DQ8
3. Multifactorial: genetic, environmental, and immune factors
4. Associated with other autoimmune diseases (e.g., type 1 diabetes)

3. Pathophysiology

1. Gluten → gliadin peptides
2. Deamidation by tissue transglutaminase (tTG)
3. Binding to HLA-DQ2/DQ8 → T-cell activation
4. Immune-mediated injury causes:
• Villous atrophy
• Crypt hyperplasia
• Intraepithelial lymphocytosis
5. ↓ intestinal surface area → malabsorption (iron, fat, vitamins)

4. Clinical Features

4.1 Gastrointestinal Features

1. Chronic diarrhea
2. Steatorrhea (foul-smelling, bulky stools)
3. Bloating, abdominal discomfort
4. Weight loss
5. Constipation (may occur)

4.2 Extraintestinal Features

1. Iron deficiency anemia (most common)
2. Fatigue
3. Dermatitis herpetiformis (pathognomonic)
4. Osteopenia / osteoporosis
5. Neurologic symptoms (e.g., peripheral neuropathy, ataxia)
6. Infertility, menstrual irregularities

5. Diagnosis

5.1 Initial Test

• Anti-tTG IgA + total IgA level
• If IgA deficiency → use IgG-based tests

5.2 Serology

1. Anti-tTG IgA → most sensitive
2. Anti-endomysial antibody → most specific
3. Anti-deamidated gliadin antibodies

5.3 Confirmatory Test

• Small bowel (duodenal) biopsy:
1. Villous atrophy
2. Crypt hyperplasia
3. Intraepithelial lymphocytosis

5.4 Additional Findings

1. Iron deficiency anemia
2. ↓ D-xylose absorption
3. ↑ stool fat (steatorrhea)

Important Diagnostic Rule

• Testing should be performed while the patient is on a gluten-containing diet (to avoid false-negative results)

6. Differential Diagnosis

1. Non-celiac gluten sensitivity
2. Irritable bowel syndrome (IBS)
3. Inflammatory bowel disease (IBD)
4. Lactose intolerance
5. Small intestinal bacterial overgrowth (SIBO)
6. Tropical sprue
7. Giardiasis
8. Pancreatic insufficiency

7. Management

7.1 First-Line

• Strict lifelong gluten-free diet

7.2 Dietary Avoidance

• Avoid: wheat, barley, rye
• Ensure avoidance of cross-contamination

7.3 Supportive Care

1. Correction of nutritional deficiencies
• Iron, folate, vitamin B12, calcium, vitamin D
2. Dietitian-guided nutritional counseling
3. Monitor serologic markers for adherence

7.4 Special Treatment

• Dapsone for dermatitis herpetiformis

8. Complications

1. Malnutrition
2. Osteoporosis
3. Infertility
4. Neurologic complications
5. Enteropathy-associated T-cell lymphoma (EATL)
6. Small intestinal adenocarcinoma

9. Key Clinical Insight

A patient with chronic diarrhea + iron deficiency anemia + dermatitis herpetiformis strongly suggests celiac disease

10. Key Exam Points

1. Anti-tTG IgA = best initial test
2. Check total IgA level
3. Biopsy confirms diagnosis
4. Associated with HLA-DQ2/DQ8
5. Causes malabsorption → steatorrhea
6. Dermatitis herpetiformis = pathognomonic
7. Must be on gluten-containing diet before testing
8. Improves with gluten-free diet
9. Risk of T-cell lymphoma (EATL)