The pentagastrin test in the diagnosis of the carcinoid syndrome.
Serotonin (5-HT) and substance P (SP) were assayed in peripheral blood in patients with known midgut carcinoids and hepatic metastases. All patients had supranormal basal levels of 5-HT and SP. The clinical and hormonal response was evaluated by two provocation tests, pentagastrin (PG) injection or calcium infusion. Pentagastrin caused flushing and gastrointestinal symptoms and elevated levels of circulating 5-HT, but not of SP. Pretreatment with a 5-HT2 receptor blocking agent (ketanserin) alleviated gastrointestinal symptoms but had no influence on either 5-HT release or PG-induced flushing. Calcium infusion induced carcinoid symptoms in only two of six patients, which were associated with elevated 5-HT levels (whereas elevated SP levels were seen in only one patient). We conclude that 5-HT is important for the development of gastrointestinal symptoms but not of flushing. Ketanserin may alleviate gastrointestinal symptoms but does not influence PG-induced release of 5-HT. Substance P and 5-HT do not seem to share a common release mechanism. It appears that PG testing is superior to calcium infusion as a provocative test in patients with the carcinoid syndrome.
Ahlman
H
H
Dahlström
A
A
Grönstad
K
K
Jaffe
B M
BM
Nilsson
O
O
Oberg
K
K
D002276:Carcinoid Tumor / Q000175:diagnosis*; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000175:diagnosis*; D006801:Humans; D006897:Hydroxyindoleacetic Acid / Q000652:urine; D007650:Ketanserin; D008297:Male; D008303:Malignant Carcinoid Syndrome / Q000175:diagnosis*; D010418:Pentagastrin / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011985:Receptors, Serotonin / Q000187:drug effects; D012702:Serotonin Antagonists / Q000494:pharmacology; D013373:Substance P / Q000097:blood; D013997:Time Factors
D010880:Piperidines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013373:Substance P; D006897:Hydroxyindoleacetic Acid; D007650:Ketanserin; D010418:Pentagastrin