The bulk of immunodeficiencies can be ruled out with little cost. The NBT or other respiratory burst
assay will help identify phagocytic-cell defects such as chronic granulomatous disease (resulting in the liver abscess in the child in question). A newer test for CGD is the dihydrorhodamine (DHR) flow cytometry study.
Wiskott-Aldrich syndrome must be considered in a patient with severe eczema and unusual infections, and is a strong possibility with this history if the platelet count is low (but is unlikely if the platelet count is normal). Other findings include eosinophilia and elevated IgE.
B-cell defects are likely to result in low immunoglobulin A, G, and M levels and result in multiple infections such as that described in the 3-year-old with otitis media and sinusitis.
An intradermal skin test using Candida albicans will result in no response in the patient with T-cell deficiencies, such as in the question of the dysmorphic child who possibly has DiGeorge syndrome. Asplenia results in Howell-Jolly bodies and also an increased risk for encapsulated organisms such as pneumococcus or meningococcus; a CBC with a peripheral smear can rule out this disease. Should any of these tests prove to be positive, more extensive, invasive, and expensive testing can be undertaken.
Very helpful
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