Determinants of delayed gastric emptying in anorexia nervosa and bulimia nervosa.

Gastric emptying was measured using a gamma camera in 22 patients with anorexia nervosa, in 10 patients of normal or high weight with bulimia nervosa and in 10 controls. Patients with anorexia nervosa were tested (1) while underweight and selecting their own diet (10 patients); (2) underweight, but receiving an adequate diet on an inpatient unit (refeeding diet) (12 patients); and (3) under refeeding diet conditions after weight gain (eight patients). Three meals, each labelled with technetium 99m-sulphur colloid, 3.7 MBq were used: (1) a mixed solid meal containing labelled poached egg; (2) 200 ml d-glucose solution, 0.5 kcal/ml, and (3) 200 ml physiological saline. Only gastric emptying rates of the solid meal and glucose solution were significantly delayed. Gastric emptying of saline was normal. The gastric disturbance was confined to patients with anorexia nervosa selecting their own diet. Patients receiving adequate nutrition on the ward had normal gastric emptying and weight gain in this group had no significant effect on emptying. Slow emptying was observed in patients who maintained a low weight solely by food restriction as well as in patients whose anorexia nervosa was complicated by episodes of bulimia. Thus, slow gastric emptying occurred when the quantity of food reaching the duodenum was sufficiently reduced to result in severe weight loss. Moreover, abnormal gastric emptying was seen only after the two meals that contained calories and were hypertonic to plasma, either of which properties could mediate the disturbance. Gastric emptying in bulimia nervosa was normal. Slow gastric emptying could exacerbate undereating in starving patients with anorexia nervosa by enhancing satiety.