Hypogammaglobulinemia is a type of primary immunodeficiency disease in which not enough gamma globulins exist in the blood (thus hypo- + gamma + globulin + -emia). This entails that not enough antibodies exist, which impairs the immune system. Hypogammaglobulinemia is a characteristic of common variable immunodeficiency. Other causes include loss of gamma globulins in urine, as in nonselective glomerular proteinuria.
Treatment is by parenteral administration of gamma globulins, either monthly intravenously, or, more recently, by weekly self-administered hypodermoclysis. In either case, mild allergic reactions (generalized pruritus, urticaria) are common, and are usually manageable with oral diphenhydramine.
"Hypogammaglobulinemia" is largely synonymous with "agammaglobulinemia". When the latter term is used (as in "X-linked agammaglobulinemia") it implies that gamma globulins are not merely reduced, but completely absent. Modern assays have allowed most agammaglobulinemias to be more precisely defined as hypogammaglobulinemias, but the distinction is not usually clinically relevant.