What is the diagnosis and treatment for a 35-year-old man with abdominal pain, flatus, and bloating that worsen after consuming foods containing barley, accompanied by a rash and numbness in his legs?

Diagnosis: Celiac Disease

This patient has celiac disease, and you should immediately order tissue transglutaminase IgA antibodies with total IgA level, followed by upper endoscopy with duodenal biopsies for confirmation before initiating a strict lifelong gluten-free diet. 1, 2

Clinical Presentation Analysis

This 35-year-old man presents with the classic triad pointing to celiac disease:

• Gastrointestinal symptoms (abdominal pain, flatus, bloating for 7 months) that worsen specifically after barley consumption—a gluten-containing grain 2, 3
• Dermatologic manifestation (rash)—likely dermatitis herpetiformis, the cutaneous manifestation of celiac disease 4
• Neurologic symptoms (leg numbness)—representing peripheral neuropathy from malabsorption-related vitamin B12 or B6 deficiency 2, 5

The direct temporal association between barley ingestion and symptom exacerbation is a key alarm feature that mandates immediate celiac disease evaluation 1.

Diagnostic Workup

Immediate Serologic Testing (While Patient Still Eats Gluten)

• Order tissue transglutaminase IgA (tTG-IgA) with total IgA level as the first-line screening test with 93% sensitivity and 98% specificity 1, 2
• Critical pitfall: Total IgA must be measured simultaneously because IgA deficiency causes false-negative celiac serology 1, 5
• Do not start a gluten-free diet before testing—this will cause false-negative results and complicate diagnosis 1, 2, 5

Confirmatory Testing

• Upper endoscopy with multiple duodenal biopsies (both bulb and distal duodenum) is mandatory if serology is positive 1, 2
• Histology will show villous atrophy, crypt hyperplasia, and increased intraepithelial lymphocytes using the Marsh-Oberhuber scoring system 1, 6
• Small bowel biopsy remains the diagnostic gold standard despite positive serology 1, 6, 7

Additional Baseline Testing at Diagnosis

Given the extraintestinal manifestations, immediately check for malabsorption-related deficiencies:

• Iron studies and complete blood count (for iron deficiency anemia) 2, 3
• Vitamin B12 and folate (to explain neurologic symptoms) 2, 5
• Vitamin D and calcium (for bone health assessment) 2
• Comprehensive metabolic panel (for liver function and albumin) 2, 5
• Thyroid function tests (high association with autoimmune thyroid disease) 3, 5

Treatment Protocol

Primary Treatment

Initiate strict, lifelong gluten-free diet eliminating all wheat, barley, and rye products 1, 2

• This is the only effective treatment for celiac disease 1, 2, 6
• Refer to a dietitian experienced in celiac disease for comprehensive nutritional counseling and education about hidden gluten sources 1, 2, 6

Addressing Specific Manifestations

• Dermatologic: The rash (dermatitis herpetiformis) will resolve with gluten elimination 4
• Neurologic: Leg numbness should improve as nutritional deficiencies are corrected with supplementation and gluten-free diet 2
• Gastrointestinal: Bloating, pain, and flatus typically resolve within weeks to months of strict gluten avoidance 2, 3

Monitoring and Follow-up

Initial Follow-up (3-6 months)

• Repeat tTG-IgA to confirm adherence to gluten-free diet 1, 2
• Verify normalization of all baseline laboratory abnormalities (iron, vitamins, liver function) 1, 2
• Assess symptom resolution and dietary compliance 1, 2

Long-term Monitoring (Every 12 months)

• Annual serologic testing and clinical assessment 2
• Ongoing nutritional monitoring for deficiency recurrence 2
• Screen for complications if symptoms persist 6, 7

Management of Non-Responsive Disease

If symptoms persist despite 6 months of gluten-free diet:

1. Review diet thoroughly for inadvertent gluten contamination—this is the most common cause of persistent symptoms 6, 8, 7
2. Confirm original diagnosis by reviewing initial serology and biopsy results 6, 7
3. Evaluate for associated conditions: microscopic colitis, pancreatic exocrine dysfunction, small intestinal bacterial overgrowth, lactose intolerance, or irritable bowel syndrome 6, 7
4. Consider repeat endoscopy with biopsies to assess mucosal healing and exclude refractory celiac disease or complications 1, 7

Critical Pitfalls to Avoid

• Never start gluten-free diet before completing diagnostic testing—this invalidates both serology and biopsy results 1, 2, 5
• Do not skip total IgA measurement—IgA deficiency occurs in 2-3% of celiac patients and causes false-negative tTG-IgA 1, 5
• Do not rely on serology alone—biopsy confirmation is required in adults before committing to lifelong dietary restriction 1, 6, 7
• Do not overlook extraintestinal manifestations—neurologic and dermatologic symptoms are common and may be the presenting features 2, 3
• Do not assume immediate symptom resolution—nutritional deficiencies may take months to correct despite strict gluten avoidance 2