Hypogammaglobulinemia

An immunodeficiency characterized by abnormally low serum immunoglobulin or antibody levels (IgG < 7 g/l or 700 mg/dL), leading to impaired humoral immune responses and increased susceptibility to recurrent or severe infections. Possible causes are transient hypogammaglobulinemia of infancy, primary immune deficiency (agammaglobulinemia, SCID, DiGeorge syndrome), medications (chemotherapy, anticonvulsants, immune suppressive therapies), B-cell malignancy, viral infections (HIV or EBV), GI loss (protein losing enteropathies or intestinal lymphangiectasia, renal loss (nephrotic syndrome), and severe burns.