Do male sex hormones protect from irritable bowel syndrome?

OBJECTIVE: Irritable bowel syndrome (IBS) is more common in women and it is frequently assumed that being female may predispose to the development of this disorder. Alternatively, being male could offer some degree of protection and if so, this might be mediated by testosterone. The aim of this study was to assess whether male patients with IBS have lower levels of testosterone and related gonadotrophins than their unaffected counterparts and if this relates to rectal sensitivity. METHODS: Fifty secondary care, male outpatients with IBS (aged 19-71 yr) were compared with 25 controls (aged 22-67 yr). Each subject had serum testosterone, free testosterone, sex hormone-binding globulin, follicle stimulating hormone, and luteinizing hormone (LH) measured, together with rectal sensitivity to balloon distension. Anxiety and depression were also assessed. RESULTS: The only difference in the hormone levels between patients and controls that reached statistical significance was the lower value for LH in the IBS patients (p = 0.014). Although patients were more anxious and depressed than the controls (p < 0.001), this could not solely account for the reduced level of LH, as adjusting for these (analysis of variance) still tended to show that LH values were lower in men with rather than without IBS F(1,70) = 2.74; p = 0.10. Men with IBS were more sensitive to balloon distension of the rectum, with the distension volumes required for "urgency" (p < 0.001) and "discomfort" (p = 0.001) significantly lower than controls. Paradoxically, the patient's sensory thresholds negatively correlated with levels of testosterone (p < 0.05) and free testosterone (p < 0.002), and positively with levels of sex hormone-binding globulin (p < 0.05). Finally, there was a tendency for IBS symptomatology to be inversely related to testosterone levels (p = 0.15). CONCLUSIONS: These results support the need for further exploration of the role of male sex hormones in the pathophysiology of IBS.