Improved diagnosis of carcinoid tumors by measurement of platelet serotonin.

Abstract

Carcinoid patients are diagnosed biochemically on the basis of increased urinary excretion of 5-hydroxyindoleacetic acid (5-HIAA); urinary and platelet serotonin concentrations are considered to provide complementary information. Using established HPLC methods with fluorometric detection, we evaluated the clinical usefulness of measurements of urinary 5-HIAA and urinary, plasma, and platelet serotonin in 30 consecutive patients with histologically proven carcinoid tumors of fore-, mid-, and hindgut origin before treatment. Ten patients showed no signs of serotonin overproduction; 14 had increased concentrations of urinary 5-HIAA and platelet serotonin; and platelet serotonin, but not urinary 5-HIAA, was increased in 6. None had increased urinary 5-HIAA excretion without an increase in platelet serotonin content. In cases with high rates of tumor serotonin secretion, platelet serotonin reached a maximum and did not correlate with serotonin secretion rate, whereas urinary 5-HIAA was correlated. Increased platelet serotonin was correlated with increased plasma serotonin and with occurrence of carcinoid syndrome. Increased urinary serotonin, allegedly caused by increases in circulating 5-hydroxytryptophan, almost invariably coincided with increased platelet serotonin, but not necessarily with above-normal urinary 5-HIAA excretion. From these results and long-term monitoring of three patients during treatment, we conclude that platelet serotonin is more sensitive than urinary 5-HIAA for detecting carcinoids that secrete only small amounts of serotonin.

• Authors: I P Kema, E G de Vries, A M Schellings, P E Postmus, F A Muskiet
• Journal: Clinical chemistry (Clin Chem) Vol. 38 Issue 4 Pg. 534-40 (Apr 1992) ISSN: 0009-9147 [Print] England
• PMID: 1373675 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Serotonin
• Hydroxyindoleacetic Acid

Topics

• Adolescent
• Adult
• Aged
• Blood Platelets (metabolism)
• Carcinoid Tumor (blood, diagnosis, urine)
• Female
• Humans
• Hydroxyindoleacetic Acid (urine)
• Male
• Middle Aged
• Reference Values
• Serotonin (blood, urine)