LAUSR

Infections are an important warning sign for a weakened immune system. In the internal medical practice acquired (secondary), particularly drug-induced immunodeficiencies, are much more frequent than congenital (primary) immunodeficiencies. The management starts as early as the planning phase before initiation of immunosuppression. The risk of infection should be individually stratified and protective vaccinations should be completed. Depending on the immunosuppressive treatment, there can be a necessity for preventive treatment, e.g. for latent tuberculosis infection or hepatitis B. The serological results on varicella zoster virus and JC polyomavirus must also be considered. The basic immunological diagnostics include differential blood count and the determination of immunoglobulins (IgG, IgA, IgM) prior to and during immunosuppressive treatment. Relevant conspicuous laboratory results before initiation of treatment should prompt advanced immunological work-up for the identification of primary immunodeficiencies, which are often accompanied by clinical signs of immune dysregulation. Depending on the type of pathogen, localization, frequency and duration as well as the severity of the infection, prophylactic antibiotic treatment may be required. Patients with chronic severe lymphocytopenia, in particular with CD4 positive T (helper) cells < 200/µl, are at increased risk for opportunistic infections so that an antibiotic prophylaxis is recommended. In patients with significantly increased proneness to infections and detection of a relevant quantitative (IgG < 4 g/l) and/or qualitative antibody deficiency (impaired vaccine response), additional immunoglobulin replacement therapy may be necessary and can be administered intravenously (IVIG) or subcutaneously (SCIG) as home treatment. In accordance with the localization of the infection, multidisciplinary clarification and management is warranted.