Background: The etiology of irritable bowel syndrome (IBS) and dysmotility is in most cases unknown. Organic, pathognomonic changes have not been described. We have previously demonstrated sporadic expressions of antibodies against gonadotropin-releasing hormone (GnRH) in serum from these patients. The aim of this study was to screen for the presence of GnRH antibodies in healthy subjects and patients with gastrointestinal (GI) diseases.

Methods: Consecutive patients suffering from either IBS, idiopathic dysmotility, GI complaints secondary to diabetes mellitus, celiac disease or inflammatory bowel disease (IBD) were included. Healthy blood donors served as controls. Blood samples were taken for analyzing IgM and IgG antibodies against GnRH using an ELISA method. Medical records were scrutinized with respect to duration of symptoms, co-existing diseases, drug treatments, hereditary factors, and laboratory analyses.

Key results: Healthy controls expressed low levels of GnRH IgM antibodies in a prevalence of 23%. The prevalence of GnRH IgM antibodies in IBS and dysmotility patients was 42% (P = 0.008), and the levels were higher (P = 0.000). Patients with diabetes mellitus expressed GnRH IgM antibodies in the same prevalence as controls (25%), but in higher levels (P = 0.02). Patients with celiac disease or IBD had the same or lower levels of antibodies. There were no associations between antibodies, other co-existing diseases or laboratory analyses.

Conclusions & inferences: Higher levels of GnRH IgM antibodies were detected in patients with IBS and dysmotility, but not organic GI diseases, compared with healthy controls. These findings suggest that IBS and dysmotility to some extent may be of an autoimmune origin.