What is the best course of action for a 5-year-old patient with abdominal pain, bloating, loose stools, and poor growth, presenting with an eczematous rash and hyperactive bowel sounds?

Celiac Disease: Diagnostic Workup and Management

Immediate Diagnostic Testing

This 5-year-old should be tested immediately for celiac disease with IgA tissue transglutaminase (tTG) antibodies and total serum IgA level, as the clinical presentation of chronic diarrhea, abdominal pain, poor growth, and eczematous rash strongly suggests this diagnosis. 1

The constellation of symptoms—foul-smelling loose stools, abdominal pain worse after meals, failure to thrive (dropping from previous growth percentiles), and eczematous rash—is classic for celiac disease in children. 2 The American College of Gastroenterology guidelines specifically recommend serologic testing in patients presenting with diarrhea, abdominal pain, weight loss, and dermatologic manifestations. 2

Initial Laboratory Panel

• IgA tissue transglutaminase (tTG) antibody is the single best serologic test for celiac disease detection, with sensitivity of 98% and specificity of 97% in pediatric populations 1, 3
• Total serum IgA level must be documented simultaneously, as IgA deficiency occurs in 2-3% of celiac patients and causes false-negative tTG results 1, 4
• If IgA deficient, measure IgG-based tests (tTG IgG or deamidated gliadin peptide IgG antibodies) 1
• Complete blood count to assess for iron deficiency anemia (pale appearance suggests this) 5, 6
• Comprehensive metabolic panel including albumin to evaluate nutritional status 6
• Ferritin, vitamin B12, folate, and vitamin D levels to identify micronutrient deficiencies common in celiac disease 3

Confirmatory Testing

When Small Bowel Biopsy is Required

If tTG antibodies are positive, proceed to upper endoscopy with small bowel biopsies to confirm the diagnosis before initiating a gluten-free diet. 1, 2 The American Diabetes Association guidelines emphasize that biopsy confirmation is essential, especially in asymptomatic or mildly symptomatic children, before endorsing the significant dietary restrictions of lifelong gluten avoidance. 1

Biopsy Technique Specifications

• Obtain 4 biopsies from the second portion of the duodenum and 2 biopsies from the duodenal bulb at the 9 o'clock and 12 o'clock positions to maximize diagnostic sensitivity 3
• Water immersion during endoscopy enhances villous detection, though normal endoscopic appearance does not exclude celiac disease 3

Exception to Biopsy Requirement

European guidelines suggest biopsy may not be necessary in symptomatic children with tTG levels >10 times the upper limit of normal, provided endomysial antibody positivity is verified on a separate blood sample. 1 However, one pediatric study found that TTG values >100 U had 98% sensitivity and 97% specificity for biopsy-proven celiac disease. 7

Critical Timing Consideration

All testing must be performed while the patient is consuming a gluten-containing diet. 2, 4 Both serologic antibodies and intestinal abnormalities resolve on a gluten-free diet, leading to false-negative results. 4

Treatment Initiation

Gluten-Free Diet Implementation

Once celiac disease is confirmed by biopsy, initiate a strict, lifelong gluten-free diet with guidance from an expert dietitian. 3 In symptomatic children with confirmed celiac disease, gluten-free diets reduce symptoms and rates of hypoglycemia. 1

• The gluten-free diet eliminates all wheat, barley, and rye products 2
• Dietitian involvement is essential for proper education on hidden gluten sources and nutritional adequacy 3
• Monitor linear growth and weight gain as key indicators of dietary adherence and response 1

Micronutrient Supplementation

Address identified deficiencies with appropriate supplementation:

• Iron for anemia (suggested by pale appearance) 3
• Vitamin D for bone health 3
• Other micronutrients (B12, folate, zinc, copper) as indicated by laboratory results 3

Follow-Up Strategy

Initial Monitoring

• Clinical follow-up at 3-6 months to assess symptom response and dietary adherence 3
• Repeat tTG antibodies to confirm declining titers on gluten-free diet 2
• Monitor growth parameters (weight and height percentiles) 1
• Reassess eczematous rash, which should improve with gluten elimination 2

Long-Term Management

Screen for additional autoimmune conditions, as celiac disease increases risk for autoimmune thyroid disease (17-30% prevalence) and type 1 diabetes. 1 The American Diabetes Association recommends screening soon after celiac diagnosis and if new symptoms develop. 1

Common Pitfalls to Avoid

• Do not start a gluten-free diet before completing diagnostic testing, as this invalidates both serologic and histologic results 2, 4
• Do not rely on negative serology alone in IgA-deficient patients—always check total IgA level 1, 4
• Do not skip biopsy confirmation in asymptomatic or mildly symptomatic children, as the diagnosis commits the patient to lifelong dietary restrictions 1
• Do not assume normal endoscopic appearance excludes celiac disease—histologic examination is required 3

Alternative Diagnoses to Consider

If celiac testing is negative, consider:

• Giardiasis (park exposure is a risk factor)—obtain stool ova and parasites examination 5
• Lactose intolerance—consider lactose hydrogen breath test 5
• Inflammatory bowel disease—obtain fecal calprotectin 5, 6
• Microscopic colitis—may require colonoscopy with biopsies if diarrhea persists 1, 5