Increased levels of plasma 5-hydroxytryptamine in patients with coeliac disease.

In 17 patients with coeliac disease the 5-hydroxytryptamine (5-HT) concentration was measured in platelet-poor plasma (PPP) and in whole blood and compared with that of a control group of 30 healthy persons. The 5-HT level was determined by high-pressure liquid chromatography and electrochemical detection. In patients with coeliac disease the concentration of 5-HT in whole blood was elevated compared with the control group (p less than 0.001). The 5-HT level in PPP was significantly increased in patients with coeliac disease in whom the disease was untreated or treated with gluten-free diet for less than a year (p less than 0.01) but also compared with the patients with coeliac disease treated with a gluten-free diet for more than a year (p less than 0.01). In some untreated patients with newly diagnosed disease the 5-HT levels in PPP were markedly elevated and exceeded the levels ordinarily found in PPP in patients with carcinoid tumours. In these patients with coeliac disease the 5-HT concentration in PPP was reduced when the enteropathy was healed. There was no significant correlation between the 5-HT concentration in PPP versus whole blood in the different groups.