From the Guidelines
Low Immunoglobulin A (IgA) levels in a normal celiac disease panel are significant because they may indicate selective IgA deficiency, which can lead to false negative results in serological tests for celiac disease.
Key Points to Consider
- Selective IgA deficiency is more common in patients with celiac disease, occurring in approximately 2.6% of cases 1.
- In patients with suspected celiac disease and low IgA levels, IgG-based tests, such as IgG anti-tissue transglutaminase (tTG) or IgG deamidated gliadin peptide (DGP), should be considered 1.
- Measuring total IgA levels is an important step in the diagnosis of celiac disease, particularly in patients with negative serologic test results and a high suspicion of celiac disease 1.
- A diagnosis of celiac disease with selective IgA deficiency can be made if the patient has a low total IgA level and positive IgG-based tests 1.
Clinical Implications
- Clinicians should be aware of the potential for selective IgA deficiency in patients with celiac disease and take this into consideration when interpreting serological test results.
- Patients with low IgA levels and suspected celiac disease should undergo further evaluation, including IgG-based tests and potentially intestinal biopsy, to confirm the diagnosis 1.
From the Research
Significance of Low Immunoglobulin A (IgA) in Celiac Disease Panel
- Low IgA levels can lead to false-negative results in serological tests for celiac disease, such as IgA-endomysial antibody (EMA) and IgA-tissue transglutaminase (TG) tests 2, 3, 4
- IgA deficiency is more common in patients with celiac disease, with a prevalence of 2-3% in celiac patients 3, 5
- Patients with selective IgA deficiency have a 10- to 20-fold increased risk of celiac disease 6
- In patients with IgA deficiency, alternative tests such as IgG-based assays (e.g., IgG-EMA, IgG-TG) may be used to diagnose celiac disease, but their reliability is limited 2, 6, 4
- Intestinal biopsy is often necessary to confirm the diagnosis of celiac disease in patients with IgA deficiency 2, 3, 4
Clinical Implications
- IgA deficiency can lead to underdiagnosis of celiac disease, as serological tests may be negative or inconclusive 2, 3, 4
- Patients with IgA deficiency and suspected celiac disease should undergo intestinal biopsy to confirm the diagnosis 2, 3, 4
- Clinicians should be aware of the potential for IgA deficiency in patients with celiac disease and use alternative diagnostic approaches when necessary 2, 3, 6, 4