What does a celiac panel with an Immunoglobulin A (IgA) level of 253 indicate?

Interpreting a Celiac Panel with IgA Level of 253

An IgA level of 253 is within normal range and indicates that IgA-based celiac disease testing is valid and reliable for diagnosis.

Understanding IgA Levels in Celiac Testing

IgA levels are measured as part of a celiac panel for two key reasons:

1. Validity of serological testing: The primary serological test for celiac disease is IgA tissue transglutaminase antibody (tTG-IgA), which has a sensitivity of 97.7% and specificity of 70.2% in children 1.

2. Ruling out IgA deficiency: Total serum IgA levels should be checked to rule out IgA deficiency, which could affect test interpretation 1.

Normal IgA Levels

• The reported IgA level of 253 is within normal range for adults (typically 70-400 mg/dL)
• This indicates that IgA-based celiac tests (tTG-IgA, EMA-IgA) can be reliably interpreted

Implications for Celiac Disease Testing

With normal IgA levels, the following interpretations apply:

• tTG-IgA results are valid: As the primary serological test for celiac disease, tTG-IgA results can be interpreted with confidence 1
• No need for alternative testing: IgG-based tests (which would be necessary in IgA-deficient patients) are not required 2

Testing Algorithm with Normal IgA

1. Primary test: tTG-IgA (sensitivity 97.7% in children, specificity 70.2%) 1
2. Confirmatory test: EMA-IgA (sensitivity 94.5%, specificity 93.8%) 1
3. Gold standard: Upper endoscopy with multiple duodenal biopsies (at least 6 specimens: 1-2 from the bulb and at least 4 from the distal duodenum) 1

Clinical Considerations

• Diagnostic accuracy: With normal IgA levels, the sensitivity and specificity of tTG-IgA and EMA-IgA tests are maintained at their expected values 3
• Biopsy requirement: Regardless of serological results, duodenal biopsy remains the gold standard for diagnosis if serology is positive 1
• Diet considerations: Biopsy should be performed while the patient is on a gluten-containing diet to avoid false negatives 1

Common Pitfalls to Avoid

1. Interpreting serology without IgA levels: Always check IgA levels before interpreting celiac serology, as approximately 2% of celiac patients have IgA deficiency 2

2. Premature dietary changes: Do not recommend a gluten-free diet before completing diagnostic workup, as this can affect test results 1

3. Inadequate biopsy sampling: Ensure at least 6 specimens are collected during endoscopy (1-2 from the bulb, 4+ from distal duodenum) 1

4. Relying solely on serology: While highly sensitive, serological tests should be confirmed with biopsy for definitive diagnosis 1