Increased volume and decreased emptying of the gallbladder in large (morbidly obese, tall normal, and muscular normal) people.

Impaired gallbladder emptying has been suggested as a possible factor in the pathogenesis of gallstones. Obese people have an increased incidence of gallstones, but there is no evidence of this in nonobese large people. This study was undertaken to determine if abnormal gallbladder motility is present in obese people. Fasting gallbladder volumes were determined using real-time ultrasound in 18 morbidly obese subjects whose weights were in a steady state [45 kg (100 lb) over ideal weight or twice expected weight for age and height; 9 males, 9 females], 18 age- and sex-matched volunteers of average size, and 18 nonobese large normal males (9 tall, 9 muscular). Gallbladder emptying studies with 99mtechnetium-diisopropyliminodiacetic acid were performed using 200 ml of 10% cream as a stimulus. The small-volume liquid fatty meal contained 113indium-diethylenetriaminepentaacetic acid to control for differences in gastric emptying in obesity. The gallbladder emptying rate in large people, both obese and nonobese, was less than that in normals of average size (p = 0.05). Fasting gallbladder volumes in large people were: obese, 41 ml (37-66 ml) (median; 95% confidence limits); nonobese large normal, 40 ml (27-43 ml). These values were greater than in normals of average size [17 ml (14-21 ml) (p = 0.03)]. Postprandial gallbladder volumes were also greater in large people: obese, 15 ml (8-23 ml); nonobese large normal, 20 ml (13-23 ml) compared with 2 ml (1-5 ml) in normals of average size (p less than 0.05). There were no differences between obese and nonobese large people. There were no differences in gastric emptying rates or in cholecystokinin, gastrin, motilin, and secretin release between obese and normal subjects. Gallbladder volume is crudely proportional to body size. Although fasting and postprandial volumes are greater in obesity, this is also present in nonobese, relatively size-matched controls. These data do not support a role for impaired gallbladder emptying in gallstone formation in obese patients whose weights are in a steady state.

Immune response after gastric bypass and weight loss.

The immune response of 22 morbidly obese patients was measured before and 6 months after gastric bypass. In-vivo skin testing was carried out using five recall antigens. In-vitro response assessed the ability of isolated lymphocytes to take up radioactive thymidine after culture with the same antigens. The mean (+/- SD) preoperative weight of the patients of 122 +/- 14 kg declined by 33.5 +/- 8 kg after 6 months. The number of positive skin tests increased from a mean (+/- SEM) of 1.8 +/- 0.17 to 2.1 +/- 0.17 (p = 0.2). Mean (+/- SEM) induration of the skin-test response assessed at 24 hours after antigen injection increased from 4.7 +/- 0.6 mm to 5.5 +/- 0.6 mm (p = 0.35) and at 48 hours from 5.4 +/- 0.7 mm to 6.9 +/- 0.9 mm (p = 0.05). One patient who was anergic before gastroplasty responded normally 6 months later after substantial weight loss. In-vitro response, expressed as a stimulation index (+/- SEM), increased from 4.71 +/- 0.65 to 7.95 +/- 1.56 (p = 0.06) for the average of all antigens and from 12.85 +/- 2.05 to 15.79 +/- 2.84 (p = 0.2) for the largest response. The authors conclude that the response to test antigens in vitro and in vivo is not reduced significantly 6 months after gastric bypass and profound weight loss. Patients with severe vomiting, rapid weight loss or sepsis may respond differently and require individual assessment.