Snapshot A 22-year-old female with a history of celiac disease comes to the office for chronic watery diarrhea. She recently returned from a vacation in Mexico. On further chart review, she has had multiple episodes of sinus infections, pneumonia, and otitis media throughout her childhood. After her last pregnancy, she received a blood transfusion following severe post-partum hemorrhage and experienced an anaphylactic reaction. Physical exam reveals chronic eczema on the flexural surface of the arms. Stool analysis is positive for Giardia. Introduction Primary immunodeficiency with decreased levels of IgA Epidemiology Most common primary immunodeficiency May be inherited (recessive and dominant forms identified) May be drug-induced Most common in individuals of European descent Prevalence 1 in 500 persons ETIOLOGY Pathogenesis login to view 3 more bullets Associated conditions login to view 6 more bullets Presentation Symptoms login to view 8 more bullets IMAGING Radiography login to view 1 more bullet STUDIES Serology login to view 3 more bullets Differential Diagnosis Common variable immunodeficiency IgG deficiency Ataxia-telangiectasia (↓ IgA, IgG, and IgE) Hyper-IgM syndrome (↓ IgA, IgG, IgE, and ↑ IgM) login to view 10 more bullets DIAGNOSIS Diagnosis based on clinical history Treatment Prevention login to view 1 more bullet Usually no specific treatment Antibiotics as needed for infections Immunizations Blood transfusions login to view 2 more bullets Complications Recurrent sinopulmonary infections Diarrhea from Giardiasis Fatal anaphylaxis Prognosis Typically very good Some patients spontaneously develop normal IgA levels