Clinical follow-up without directed treatment is indicated for this patient. She has selective IgA deficiency, which has no specific therapy except for antibiotic treatment as needed for those with recurrent sinopulmonary infections. Selective IgA deficiency is the most common of the congenital immune defects, with an incidence of about 1:500. The disease is usually sporadic, but autosomal dominant and autosomal recessive inheritance is found. Most people with IgA deficiency are asymptomatic, although the most common clinical manifestation is sinopulmonary infection, which is often the reason quantitative serum immunoglobulin levels are obtained. IgA deficiency is defined as a serum IgA level less than 7 mg/dL (0.07 g/L). A less common but potentially severe finding in selective IgA deficiency is anaphylaxis with blood product transfusion. IgA deficiency is also frequently associated with autoimmune illnesses, including systemic lupus erythematosus, rheumatoid arthritis, hemolytic anemia, and immune thrombocytopenic purpura. Additional manifestations include atopic eczema, asthma, urticaria, and a variety of other allergic disorders. Gastrointestinal disorders, including infection with Giardia lamblia, may also occur. Despite these multiple potential clinical consequences associated with IgA deficiency, the indicated treatment approach is primarily preventive and supportive.

Patients with terminal complement deficiencies are at higher risk for meningococcal disease, but those with immunoglobulin deficiency are not. Therefore, the meningococcal conjugate vaccine is not indicated specifically for IgA deficiency.

Secreted IgA is produced and generally acts locally. Therefore, administration of intravenous concentrates of IgA would not achieve adequate levels in mucosal secretions, so it would not be helpful in this patient.

IgA deficiency is selective, occurring without deficits in other immunoglobulins in these patients. Therefore, administration of intravenous immune globulin would not be indicated in this patient. Intravenous immune globulin is used in patients with severe deficiencies in most immunoglobulins, as is seen in X-linked agammaglobulinemia and common variable immunodeficiency.

Stem cell or bone marrow transplantation is appropriate treatment for severe combined immune deficiency syndrome, but not selective IgA deficiency. Selective IgA deficiency is usually asymptomatic or has mild symptoms that are easily treated or managed; therefore, the potential risks and long-term immunosuppression associated with stem or bone marrow transplantation are greater than the potential benefits of this treatment for selective IgA deficiency.