Office management: Allergy and immunologyEvaluation of the Adult with Suspected Immunodeficiency
Section snippets
A Brief Overview of the Immune System
The main task of the immune system is the differentiation of “self” from “non-self.” “Non-self” is considered harmful and should be eliminated, whereas “self” is tolerated. Microorganisms are the major “non-self” that the immune system attempts to neutralize on a daily basis. A suboptimal immune system is not able to effectively contain microorganisms, resulting in frequent infections. Also, an abnormal immune system might not be tolerant of “self,” resulting in autoimmune diseases. Some immune
Primary Versus Secondary Immunodeficiency
Primary immunodeficiency disorders (PIDs) are reported to have an estimated prevalence of 1:10,000 in the general population. This is probably an underestimate because the prevalence of selective immunoglobulin (Ig)A deficiency is estimated at 1:300 to 1:700 (in the United States). Approximately one third of patients with selective IgA deficiency have frequent infections, thus making the prevalence of clinically relevant primary immunodeficiency much more common than 1:10,000. In addition to
When to Suspect an Immunodeficiency
Although recurrent infections are a hallmark of immunodeficiency, this is not always the case. In thinking about immunodeficiency, the key word is “unusual” (Table 3). An unusual organism, an unusual duration, an unusual complication, or an unusual severity of a “usual” infection should prompt suspicion of an immunodeficiency. For example, an upper respiratory tract infection that progresses to pneumonia or empyema in an otherwise healthy individual may indicate an underlying immune
History
As in any disease investigation, a thorough history is the most important initial step in evaluation. Detailed information should be obtained about the nature and site of the infections, their frequency, their complications, their documentation (cultures, imaging), and their treatment. Treatment features that might suggest a less than optimal host defense include the need to use intravenous antibiotics, the need for multiple antibiotics, and the need for multiple courses of antibiotics.
History
Summary
A heightened index of suspicion of immunodeficiency can lead to an early diagnosis and a favorable outcome. Recurrent infections, unusual aspects of usual infections, unexplained bronchiectasis, chronic diarrhea, autoimmune diseases, and “failure to thrive” should prompt screening for a potential immune abnormality. A considerable wealth of information can be obtained from screening tests done in a primary care setting. If initial assessment does not reveal any abnormality, and the clinician
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Richard D. deShazo, Speciality Editor