Initial intravenous immunoglobulin doses should be based on adjusted body weight in obese patients with primary immunodeficiency disorders

Background Immunoglobulin therapy plays a critical role in the treatment of immunodeficiency disorders as well as autoimmune and inflammatory conditions. In immunodeficient patients, there has been controversy whether initial loading doses of intravenous (IVIG) should be based on actual body weight or a calculated parameter such as adjusted body weight in obese patients. Case presentation I describe a patient with Common Variable Immunodeficiency disorder (CVID) who underwent bariatric surgery for morbid obesity. Her weight decreased by 50% to below her calculated ideal body weight (IBW) while her immunoglobulin requirement fell by approximately 20%. Her steady state serum IgG increased from approximately 7 g/l to 11.7 g/l concomitant with weight loss. Conclusions I present this observation as support for the recommendation that initial loading doses of SCIG/IVIG in immunodeficiency should be based on adjusted body weight (AjBW) and not actual body weight in obese patients. This has important fiscal implications for treating obese patients with immunodeficiency disorders.