A second look at secondary hypogammaglobulinemia.

Hypogammaglobulinemia is defined as a reduced immunoglobulin level, which can be either primary due to inborn errors of immunity or acquired in the setting of poor antibody production or increased antibody loss. Secondary hypogammaglobulinemia (SHG) should be considered in patients with a history of immunosuppressive therapy, transplant, protein loss syndromes, certain autoimmune conditions, and malignancies, as it can be associated with increased infectious risk. Appropriate history and lab-based screening in these populations can identify SHG allowing treatment and close monitoring as appropriate. Ideally, treatment focuses on control of the underlying condition or removal of iatrogenic causes of SHG. However, in many cases, treatment of the underlying condition does not reverse SHG or immunosuppressive therapy cannot be discontinued without significant risk to the patient. For these patients, strategies for risk mitigation against infectious complications include vaccination, antibiotic prophylaxis, and immunoglobulin replacement therapy. This report aims to summarize the existing and emerging data in the evaluation and management of SHG and highlight areas that require further investigation.