Secondary antibody deficiency - causes and approach to diagnosis.

Antibody deficiencies can occur in the context of primary disorders due to inherited genetic defects; however, secondary immune disorders are far more prevalent and can be caused by various diseases and their treatment, certain medications and surgical procedures. Immunoglobulin replacement therapy has been shown to be effective in reducing infections, morbidity and mortality in primary antibody deficiencies but secondary antibody deficiencies are in general poorly defined and there are no guidelines for the management of patients with this condition. Clinical decisions are based on experience from primary antibody deficiencies. Both primary and secondary antibody deficiencies can be associated with infections, immune dysregulation and end-organ damage, causing significant morbidity and mortality. Therefore, it is important to diagnose and treat these patients promptly to minimise adverse effects and improve quality of life. We focus on secondary antibody deficiency and describe the causes, diagnosis and treatment of this disorder.