Patients with recurrent infections are often referred for further investigation of their immune function, to establish if there is an underlying immune deficiency. There are 3 major clinical scenarios in this setting:
- Recurrent regional infections can be due to anatomical abnormalities such as ureteric obstruction with repeated kidney infections, or recurrent sinusitis following previous significant sinus surgery.
- There are secondary causes of immune deficiency that can lead to repeated infections such as HIV infection, diabetes, immunosuppressive drugs, malignancy and chronic liver or kidney disease.
- Primary immune deficiency, due to genetic mutations, can present for the first time in adults with frequent infections and often there is considerable diagnostic delay until the diagnosis is made and appropriate therapy offered.
In order to make a correct diagnosis it is necessary to take a full history (including family history of immune deficiency), do a thorough clinical examination, and then perform the appropriate medical and specific immune tests. The specialized immune tests can comprise measurement of antibody levels and complement, response to vaccination, evaluation of cell mediated immunity and phagocytic function.
The management of patients with documented antibody deficiency is monthly IVIG replacement therapy. These patients often have recurrent respiratory infections and IgA deficient patients can also have GIT parasitic infections and malabsorption, which is best managed by a multidisciplinary team consisting of a clinical immunologist, pulmonologist, and gastroenterologist. It is important to diagnose the condition and initiate treatment early to pre-empt recurrent pulmonary infections resulting in permanent lung damage and bronchiectasis.
Patients with autoimmune rheumatological disorders are also seen, such as rheumatoid arthritis, dermatomyositis, and Systemic Lupus Erythematosus (SLE). They can present with skin and muscle disorders and arthritis, but may also have systemic involvement such as cardiac, pulmonary and kidney disease. They often require immune suppression to control the disease and need careful follow up and monitoring. We are also seeing patients with a newly emerging autoimmune disease termed IgG4-related sclerosing disorders, for which there are specific diagnostic criteria. Patients present with inflammation involving sinuses and eyes, but may also have systemic involvement of lungs or pancreas, and require immune suppression to control the disease activity.