From the Guidelines
Isolated IgA deficiency typically requires monitoring rather than specific treatment, focusing on surveillance and addressing any recurrent infections, as stated in the practice parameter for the diagnosis and management of primary immunodeficiency 1. When a patient presents with reduced IgA levels but normal IgG and IgM, the management approach should focus on surveillance and addressing any recurrent infections. No specific medication exists to correct IgA deficiency itself.
Key Management Points:
- Patients should be monitored for infections, particularly respiratory and gastrointestinal, with prompt treatment using appropriate antibiotics when infections occur.
- For those with frequent infections, prophylactic antibiotics may be considered, such as trimethoprim-sulfamethoxazole (one single-strength tablet daily) or amoxicillin (250-500mg daily).
- Immunoglobulin replacement therapy is generally not indicated for isolated IgA deficiency as commercial preparations contain minimal IgA and wouldn't correct the deficiency, although rare patients with SIGAD might benefit from IVIG replacement therapy 1.
- Additionally, patients should be educated about their increased risk of autoimmune disorders, allergies, and potential reactions to blood products containing IgA.
- Regular follow-up every 6-12 months is recommended to assess infection frequency and monitor for developing complications. The underlying mechanism of isolated IgA deficiency involves a maturation defect in B cells that prevents them from producing IgA antibodies, though the exact cause remains unclear in most cases.
Important Considerations:
- Patients with serum IgA levels of less than the normal range for age but greater than 7 mg/dL should not be given a diagnosis of IgA deficiency, as there are no consistently identified clinical associations in those with IgA concentrations of greater than 7 mg/dL but less than the lower limit of normal 1.
- Patients with SIGAD should be monitored over time for the occurrence of complications, including respiratory and gastrointestinal tract infections, atopy, autoimmune diseases, celiac disease, and malignancy 1.
From the Research
Interpretation of Isolated Reduction in IgA
- Isolated reduction in IgA, also known as selective IgA deficiency (SIgAD), is the most common primary immunodeficiency, but it does not always result in clinical disease 2.
- The definition of SIgAD is based on serum IgA levels, while most IgA is secreted at mucosal surfaces, which cannot be measured 2.
- Clinical complications of SIgAD include increased risk of sinopulmonary infections, gastrointestinal infections, autoimmune diseases, and rarely, malignancy 2.
Management Plan
- Patients with SIgAD should be monitored at regular intervals and educated to be aware of particular complications 2.
- Prophylactic antibiotics may be indicated in some cases, and very rarely, supplemental IgG infusions may be necessary 2.
- Immunoglobulin replacement therapy (IRT) and antibiotic prophylaxis (PA) have been shown to be effective in preventing infections in patients with IgG subclass deficiency, and the choice between the two treatments should be based on individual patient needs 3.
- It is essential to differentiate SIgAD from IgA deficiency that may be seen with IgG2 or IgG4 deficiency, specific antibody deficiency, or as an early manifestation prior to a diagnosis of common variable immunodeficiency 2.
Considerations
- Secondary IgA deficiency is increasingly recognized and may be due to medications, infections, or malignancies, and should be considered in the differential diagnosis 2.
- The genetic basis of IgA deficiency remains to be clarified, and better understanding of the production and function of IgA is essential in elucidating the disease mechanism in IgA deficiency 4.
- Recent studies have provided new insights into the complex role of IgA in health and disease, including its protective and harmful roles, and new IgA-based therapeutic approaches are being developed 5.