Buerger's disease associated with IgA nephropathy: report of two cases.

The cause of flushing attacks in patients with carcinoid syndrome is unknown. In a subgroup of patients (many ofwhom have metastatic gastric carcinoid tumours) histamine excretion is frequently and consistently raised.45 Two reports have shown significant reductions in both frequency and duration offlushing attacks during combined treatment with H, and H2 receptor antagonists in two patients with metastatic gastric and ileal carcinoid tumours.'2 In one of these patients,' the duration (but not the frequency) of flushing attacks was reduced by cimetidine alone. The authors concluded that in some patients with carcinoid tumours histamine may be the cause of the flushing attacks. In one patient,2 however, histamine excretion in the urine was normal during the flushing attacks, whereas the serum serotonin concentration was raised. We know of no data on serum serotonin concentrations during treatment with antihistamines. In our patient administration of ranitidine alone caused prompt cessation of flushing attacks and a significant reduction in serum serotonin concentrations. This suggests that the beneficial effects ofH2 receptor antagonists seen in some patients with the carcinoid syndrome, may not necessarily be caused by inhibition of the action of histamine but may be partially mediated by a reduction in serum serotonin concentrations.