A Brief Synopsis of AFP's "Evaluation of Primary Immunodeficiency Disease in Children"

A brief synopsis of :
Evaluation of Primary Immunodeficiency Disease in Children 
CARIN E. REUST, MD, MSPH, University of Missouri School of Medicine, Columbia, Missouri 
Am Fam Physician. 2013 Jun 1;87(11):773-778 
http://www.aafp.org/afp/2013/0601/p773.pdf

     According to this article, there are over 180 primary immunodeficiency diseases that have been identified. The types that will be reviewed here are antibody (B cell), combined B and T cell, phagocytic, and complement disorders.  Antibody disorders are the most common. They are categorized by the presence or absence of B cells, and the quality of the B cells if present.  Patients with this type of disorder will have recurrent or severe encapsulated bacterial infections of the ears, lungs and sinuses. They include S. pneumoniae and H. influenzae. Agammaglobulinemia is a complete absence of B cells. A decrease in all immunoglobulin subtypes may be seen in testing as well. The infant patient may present with an absence of tonsils or lymph nodes. In hypogammaglobulinemia, some or all of the immunoglobulins may be at low or at deficient levels. Some examples of hypogammaglobulinemia are CVID, IgA deficiency, and IgG subclass deficiency. The patient may have an abnormal response to vaccinations. They may present with GI symptoms (diarrhea, malabsorption, IBS symptoms) or ear, sinus and pulmonary infections. They can be caused by C. difficile, Giardia, Salmonella, Campylobacter, and Yersinia. These patients will have problems with vaccine effectiveness. Titers should be checked in these patients. 
     T-cell disorders can have an absence of T-cells (such as in SCID) or T-cells and B-cells combined. Patients may present with  diarrhea, failure to thrive, and infection. Bloodwork will show lymphocytopenia or lymphocytosis. An absolute lymphocyte count of less than 3000/mm3 in a newborn is a good indicator. Patients will not have a response to a delayed hypersensitivity skin test. 
     Phagocytic disorders are due to problems with neutrophils and monocytes. They will have neutropenia (neutrophil count less than 1500 per mm3) and abnormalities in lysosomal granules.  One example is chronic granulomatous disease. It presents in a patient by the age of 5 with pneumonia, adenitis, omphalitis, and GI infections. The bacteria that invade are catalase positive, such as S. aureus, B. cepacia, Nocardia, Aspergillus, or Candida. Patients with leukocyte adhesion deficiency type 1 may present in infancy with prolonged separation of the umbilical cord, perianal ulcers, or omphalitis.
     Complement disorders involve infections with encapsulated organisms. A C3 deficiency will have recurrent pyogenic infections from S. pneumoniae or H. influenzae. A deficiency in C5-C9 are associated with N. meningitidis. The complement levels can be checked with a CH50 assay. 
     When determining whether to evaluate a patient for a primary immunodeficiency disease, look for children with recurrent ear, sinus and pulmonary infection, diarrhea, and failure to thrive. Infections in multiple anatomic locations are an important clue, especially if there are serious infections from unusual pathogens.  Three warning signs to look for are a positive family history, sepsis that needed IV antibiotic treatment, and failure to thrive.