Selective IgA deficiency is the most common primary immunodeficiency, present in roughly 1 in 500 people. Most patients have no symptoms and never need treatment. Some, however, experience recurrent infections, gastrointestinal problems, or autoimmune disease that benefits from specialist evaluation.
Immunoglobulin A (IgA) is one of the antibodies the immune system uses to protect mucosal surfaces — the lining of the airways, sinuses, and gut. In selective IgA deficiency, the body produces little or no IgA while other antibody levels remain normal. It is the most common primary immunodeficiency, and most people who have it never know.
When IgA deficiency does cause symptoms, the most common pattern is recurrent sinus and respiratory infections. Some patients also develop chronic gastrointestinal symptoms, autoimmune conditions such as celiac disease or thyroid disease, or unusual allergic reactions. A subset of patients with IgA deficiency progress to a more comprehensive antibody deficiency over time, which is why ongoing monitoring matters even when initial symptoms are mild.
Diagnosis is based on a quantitative measurement of serum IgA below the laboratory threshold (typically less than 7 mg/dL) in a patient over four years of age, with normal IgG and IgM and exclusion of other causes of low immunoglobulins.
Once the diagnosis is made, additional workup at Optimed Immunology typically includes IgG subclasses, specific antibody response testing to vaccine antigens, and screening for associated conditions such as celiac disease and thyroid autoimmunity. Periodic monitoring is recommended because a small percentage of patients with IgA deficiency develop broader antibody deficiency over time.
Most patients with selective IgA deficiency require no specific treatment. Care focuses on prompt and appropriate management of infections when they occur, and on identifying and managing any associated autoimmune or gastrointestinal conditions.
For symptomatic patients with frequent infections, prophylactic antibiotic strategies may be considered. Patients with combined IgA deficiency and IgG subclass deficiency, or those with impaired vaccine response, may be candidates for immunoglobulin replacement therapy — with careful product selection because patients with IgA deficiency can react to standard immunoglobulin preparations.
A first visit typically lasts 45 to 60 minutes. Dr. McNeil takes a careful history of your infection patterns, gastrointestinal symptoms, allergic reactions, and family history of immune-related conditions. After examination, the rationale for any additional testing is discussed, and you receive a clear plan in writing. For most patients, ongoing care is straightforward and visit-light, with monitoring once per year unless symptoms change.
Donald L. McNeil, MD · Board Certified in Allergy & Immunology and Internal Medicine
This page is provided for educational purposes and does not substitute for clinical judgment or direct medical advice. Treatment decisions are individualized based on your full history, examination, and laboratory findings. If you have an emergency, call 911.