Primary immunodeficiency diseases: when we should suspect

A functional immune system is fundamental for homeostasis because it plays essential roles in defense against infectious agents, besides protecting the human body against tumor cells and autoimmune diseases. During childhood, the immune system is physiologically immature, but it develops progressively as the individual grows. Thus, in this period, recurrent infections can occur, mainly in the airways, even in completely healthy children.1,2 Children that born with a defective immune system develop conditions that belong to a group of diseases known as primary immunodeficiencies (PIDs).3–5 These congenital diseases (which develop mainly during childhood) manifest especially in the form of recurrent infections, which often coincide with the immunological maturity period of the patients.6–8 Therefore, recognizing the suggestive characteristics in the clinical history and during the physical examination is fundamental to raise the hypothesis of primary immunodeficiency.3 Given the many characteristics that serve as warning signs, the Jeffrey Modell Foundation in association with the American Red Cross has created a list of Ten Warning Signs to facilitate the medical reasoning during the care of patients who need initial laboratory investigation9 The investigation should be carried out through initial examinations of easy access, which may be requested by the professional in the primary approach.7 The diagnosis should be complemented with specialized examinations in reference centers, where the child should receive prompt treatment.10 An early diagnosis is fundamental for an adequate treatment and consequent improvement in the quality of life of the patient, as well in the long-term prognosis and prevention of sequelae. Therefore, the recognition of the need of a systematic investigation for primary immunodeficiency of the patient depends on a well-founded suspected diagnosis by the physician in the primary approach.