Carcinoid Syndrome presents with signs and symptons associated with malignant neoplasms of enterochromaffim cells, which typically contain serotonin.
The most common endocrine consequences and clinical manifestations of these tumors include:
When all of its clinical features are present, carcinoid syndrome is easily recognized. The diagnosis also must be considered when any one of its manifestation is present.
The diagnosis is made measuring the urinary excretion of 5-HIAA (5-hydroxyindoleacetic acid), the major metabolite of serotonine, which is overproduced. Normally, excretion of 5-HIAA does not exceed 9 mg daily. When dietary 5-hydroxyndoles are excluded (foods containing serotonin such as bananas or walnuts), urinary excretion of 25 mg of 5-HIAA daily, is diagnostic of carcinoid syndrome. Elevation in the range of 9-25 mg may be seen with carcinoid syndrome, nontropical sprue, or acute intestinal obstruction.
Measurement of serotonin in blood or platelets, has less diagnostic value than assay of the major metabolite of serotonin in the urine.
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