5-Hydroxyindoleacetic Acid

5-Hydroxyindoleacetic acid (synonyms: 5-HIES, HIES) is a metabolic product formed by the breakdown of serotonin.

The process

Material needed

  • 24 h urine
  • Prepare collection vessel beforehand with 12 ml hydrochloric acid

Preparation of the patient

  • The following substances must not be taken for three days before the diagnostic procedure:
    • Fruits such as pineapples, bananas, currants, kiwis, melons, mirabelles, plums, gooseberries, plums.
    • Vegetables such as eggplant, avocados, tomatoes.
    • Nuts such as pecans, walnuts
    • Cheese
    • Cocoa
    • Drugs: chlorpromazine, methamphetamine, methocarbamol, mephenescincarbamate, reserpine.
  • Coffee and nicotine can also lead to falsified results

Interfering factors

  • None known

Normal value

Normal value in mg/24 h < 9
  • Values > 40 mg/24 h are probative of a carcinoid

Indications

  • Suspected ileal carcinoid (serotonin-producing neuroendocrine neoplasms (NEN); serotonin-producing NEN).

Interpretation

Interpretation of increased values

  • Epilepsy
  • Carcinoids (synonyms: diffuse neuroendocrine neoplasia (neoplasm); neuroendocrine tumors, NET; gastoenteropancreatic neuroendocrine neoplasia (GEP-NEN)). – Localization: Depending on the localization, the following are distinguished: bronchus carcinoid, thymus carcinoid, appendix carcinoid, ileum carcinoid, duodenal carcinoid, gastric carcinoid, rectum carcinoid (colon NET), pancreas carcinoid (pancreas NET); about 80 percent of the tumors are localized in the terminal ileum or appendix.Symptoms: The first sign is often a persistent diarrhea. Typical for the carcinoids (GEP-NEN) is the “flush symptomatology” (flush syndrome); this is a sudden blue-red discoloration of the face, neck and under certain circumstances of the torso understood, furthermore hypoglycemias (hypoglycemia) or duodenal ulcers (ulcers of the duodenum).
  • Celiac disease (gluten-induced enteropathy) – chronic disease of the mucosa of the small intestine (small intestinal mucosa), which is based on hypersensitivity to the cereal protein gluten.

Interpretation of lowered values

  • Not relevant to the disease

Further notes

  • In the symptom-free interval of a carcinoid, the HIES may be unremarkable! (If clinical suspicion is urgent, repeat examination is indicated!).