Diagnosis
There are a wide variety of immunodeficiencies; this page is some of the congenital. ImmImmunity touches on a vast number of ways the host immune system can be altered to negatively affect function. For example, polymorphisms, single amino acid substitutions, in everything from the TOLL system to the vitamin D receptor to cytokines to snot can decrease (or augment) the host's response to infection. But until such time as Dr. McCoy's tricorder becomes a reality these subtle variations cannot be diagnosed by us mere mortals.
Brutons: no IgG at all. Mostly a pediatric disease, the occasional patient goes undiagnosed into adulthood, often due to a lack of insurance.
Common Variable Immunodeficiency: An immunoglobulin deficiency. Patients often have IgG subtype and other class deficiencies.
So order IgG, IgE, IgM, IgA and IgG subtypes. As low antibody levels do not necessarily mean poor function, it is nice to prove it by measuring the response to vaccines (PubMed).
And there is specific antibody deficiency (SAD) with impaired IgG responses to polysaccharides with normal serum concentrations of IgG, IgM, and IgA
CLL, Myeloma and Waldenstroms can also have low functional antibody levels.
Syndromes
Common Variable Immunodeficiency: recurrent URI infections is the hint. These are the infections of encapsulated organisms, the ones that require antibody for optimal killing. Bronchitis, Sinusitis, Pneumonia, Bronchiectasis, Sepsis, Endocarditis, Meningitis, Chronic diarrhea, Splenomegaly, Autoimmune cytopenia, Liver disease. It can also get chronic diarrhea with Giardia.
CVIDS also get autoimmune and/or lymphoproliferative diseases (PubMed).
Microbiology
Common Variable Immunodeficiency: In rough order of descending incidence Streptococcus pneumoniae, Haemophilus influenzae, Giardia intestinalis, Salmonella species, Campylobacter species, Clostridium difficile, Yersinia enterolitica, Chronic Hepatitis C, Neisseria meningitidis, Staphylococcus aureus skin abscess, recurrent Varicella Zoster, invasive HPV infection or profuse warts, severe Varicella Zoster, oral Candida, severe infectious mononucleosis (Epstein Barr virus), Ocular Toxoplasma, visceral mycosis, visceral Cytomegalovirus infection, Pneumocystis pneumonia, Cryptosporidium diarrhea, cerebral Toxoplasma, systemic adenovirus infection, Kaposi sarcoma.
Ig A: Giardia, Salmonella, and Campylobacter lead the list with undetectable serum IgA.
Treatment
Common Variable Immunodeficiency: Monthly immunoglobulin infusions; is only moderately effective in decreasing infections as titers against a given organism may be low or lacking depending on who donated the serum.
Curious Cases
Relevant links to my Medscape blog