Is the pattern of solid-phase gastric emptying different between genders?

Background In the C-13-octanoate breath test, the shape of the (CO2)-C-13 excretion curve in the ascending portion reflects a pattern of gastric emptying (GE). Recent scintigraphic studies have revealed an overall delay in solid GE in fertile women compared with men. However, it remains unknown whether women have a different GE pattern compared with men. As a symptomatic delay in solid GE is specific to the female gender, it could be hypothesized that the (CO2)-C-13 excretion curve is different in shape between genders. Materials and methods Because the ascending gradient of the (CO2)-C-13 excretion curve is often biphasic, the dual function of gamma(t) = (a(1) center dot t(b1) + a(2) center dot t(b2))e-(Kt) was applied to fit the breath data, where a(1), b(1), a(2), b(2), and K are constants. Assessed on the 4h-based breath samples obtained after ingestion of a 320-kcal muffin containing 100 mg C-13-octanoate, the time versus (CO2)-C-13 excretion curve was created from 31 adult volunteers (15 men and 16 women). The curve shape was characterized by the dual function, and was compared between genders. Results In both genders, the ascending gradient exhibited the biphasic feature, characterized by an initial steep rise and the subsequent blunted increase, while the descending gradient followed the monotonous decay. The initial rise was steeper and the subsequent increase was more blunted in women than in men. Conclusions Women exhibit a gender-specific pattern of the (CO2)-C-13 excretion profile. A possible explanation for this gender difference is that the post-gastric feedback regulation is more potent in women than in men.