Low level IGF-I and common variable immune deficiency: An unusual combination

A relation between growth hormone (GH) deficiency and immunoglobulin deficiency has been suggested previously in a few cases. We describe a patient with an insulin-like growth factor I (IGF-I) deficiency and common variable immune deficiency and briefly review earlier publications on the possible interaction between IGF-I and the immune system. IGF-I is the downstream mediator of GH. In this patient, GH and IGF-I levels were both low. The GH response to a GH-releasing hormone test was normal whereas no subsequent IGF-I response was seen. In our cohort of 14 patients with hypogammaglobulinaemia, two turned out to have slightly decreased IGF-I serum levels and one patient with a thymoma had an increased IGF-I level. Even though IGF-I may be connected to B lymphocyte differentiation, in this patient we hypothesise there is a common impairment in the IGF-I and IgG pathways.