Histamine and duodenal ulceration in renal transplant recipients.

Six of 25 renal transplant recipients had a duodenal ulcer at endoscopy. Histamine concentration and the activity of histamine methyltransferase, the degrading enzyme of histamine, were measured in gastric mucosal biopsies obtained at endoscopy and compared with patients with duodenal ulcer but not undergoing transplant and with patients with an apparently normal stomach and duodenum. Histamine concentrations in the corpus (no ulcer, median: 151 nmol/g; DU, median: 122 nmol/g) and in the antrum (no ulcer, median: 118 nmol/g; with DU, median: 113 nmol/g) of renal transplant patients, irrespective of ulcer diagnosis, and in patients with a chronic duodenal ulcer (median corpus histamine: 137 nmol/g and median antral histamine: 126 nmol/g) were not different from one another but significantly lower than the corresponding values in normal subjects (median corpus histamine: 241 nmol/g, p less than 0.01, and median antral histamine: 178 nmol/g, p less than 0.05). Histamine concentration in the corpus was significantly higher than in the antrum in all three groups of patients (p less than 0.05). There were no significant differences in histamine methyltransferase activity in any of the groups studied. Mucosal histamine and histamine methyltransferase activity were significantly correlated in the corpus (p less than 0.05) and antrum (p less than 0.02). Plasma concentration of histamine after transplant was higher in the patients who subsequently were discovered to have a duodenal ulcer (p less than 0.05). The occurrence of ulcer after transplantation was not related to the serum creatinine level. The uniform depletion of gastric histamine and increase in circulatory histamine after renal transplantation may be a factor in the pathogenesis of duodenal ulcer disease in this clinical situation.