5-hydroxyindoleacetic acid in the urine

The reference values (norm) of the concentration of 5-hydroxyindoleacetic acid in a single dose of urine in adults are less than 25 mg / day (<131 μmol / day), the content in daily urine is 2-7 mg / day (10.5-36.6 μmol / day).

5-Oxyindoleacetic (5-hydroxyindolylacetic) acid is the final product of the metabolism of serotonin. The determination of its concentration in the urine is more useful than the study of the level of serotonin in the blood for the diagnosis of carcinoid tumors. The study requires special preparation of the patient - exclusion of foods containing 5-hydroxyindoles (walnuts, bananas, avocados, aubergines, pineapples, plums, tomatoes) and some medicines (corticotropin, salicylates, imipramine, levodopa, monoamine oxidase inhibitors, isoniazid, ethanol ). The content of 5-hydroxyindoleacetic acid in a single portion of urine greater than 25 mg / day (more than 131 μmol / day) is considered diagnostically significant for carcinoid syndrome. Increase of 5-hydroxyindoleacetic acid is noted in carcinoid tumors of the middle (most often ileum) and upper (pancreas, duodenum, biliary tract) parts of the gastrointestinal tract. In carcinoid tumors with metastases, the level of 5-hydroxyindoleacetic acid often exceeds 350 mg / day (1820 μmol / day).

An increase in the concentration of 5-hydroxyindoleacetic acid is detected in carcinoid tumors of the testicle, celiac disease, Whipple's disease, ovarian cancer of the bronchi, bronchial adenoma of the carcinoid type. Tumors of the lower intestine (rectum) rarely produce 5-hydroxyindoleacetic acid.