5-hydroxyindoleacetic acid (5-HIAA) Test

5-HIAA Urine Test, Serotonin Metabolite 5-HIAA Test

BodyBrainAI Team31 Aug 2023
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The 5-HIAA or 5-hydroxyindoleacetic acid urine test is used to detect and monitor carcinoid tumors which secrete excess serotonin. It measures levels of the serotonin metabolite 5-HIAA in a urine sample.

What is the 5-HIAA Test?

The 5-HIAA test is a specialized urine test that measures the amount of 5-hydroxyindoleacetic acid in the urine over a 24-hour period.

5-HIAA is the main metabolite of serotonin, a neurotransmitter and hormone. Certain carcinoid tumors and other neuroendocrine tumors produce excess serotonin which gets converted into 5-HIAA.

By collecting urine for 24 hours and measuring 5-HIAA levels, doctors can detect elevated serotonin production that may signify carcinoid tumors.

It requires following a special diet and medication restrictions before and during the urine collection period. The sample is analyzed in a laboratory using specialized techniques.

What is the 5-HIAA Test Used For?

The main uses of the 5-HIAA urine test are:

  • Diagnosing carcinoid tumors, typically in the GI tract, lung or pancreas

  • Identifying recurrence of carcinoid tumors after treatment

  • Monitoring carcinoid tumor treatment effectiveness and progression

  • Distinguishing carcinoid syndrome from conditions like IBS

  • Assessing prognosis and survival rates for carcinoid cancer

How is the 5-HIAA Test Performed?

  • Patient follows a restricted diet for 2-3 days before and during urine collection.

  • 24-hour urine sample is collected in a large container with preservative.

  • Sample is analyzed using liquid chromatography, mass spectrometry, ELISA, or spectrophotometry methods.

  • Results are reported in mg/24 hours with up to 15 mg/day being normal.

  • Elevated results signify increased serotonin secretion from tumors.

What Does the 5-HIAA Test Screen For?

Specifically, the 5-HIAA urine test detects:

  • Increased serotonin and 5-HIAA levels indicating a carcinoid tumor

  • Efficacy of treating carcinoid syndrome with somatostatin analogs

  • Recurrence of tumor growth when levels increase again after treatment

  • Status and progression of metastatic carcinoid disease

Why Do I Need a 5-HIAA Test?

Your doctor may order this test if you have:

  • Symptoms of carcinoid syndrome - flushing, diarrhea, wheezing

  • An unexplained mass or lesion in the GI tract, lungs or pancreas

  • Previously treated carcinoid tumor to check for recurrence

  • Confirmed carcinoid cancer to monitor treatment effectiveness

  • Need to distinguish carcinoid syndrome from similar conditions

What is Needed to Prepare for the 5-HIAA Test?

  • Avoid bananas, pineapple, kiwi, plums, eggplant, tomatoes, avocados for 2-3 days before and during the urine collection as they affect serotonin metabolism.

  • Discontinue medicines like cough syrup and Pepto-Bismol.

  • Do not take serotonin, L-dopa or MAO inhibitor drugs which can elevate 5-HIAA.

  • Obtain supplies for collecting all urine for 24 hours. Keep samples refrigerated during collection.

How Long Does it Take to Get 5-HIAA Test Results?

  • 24-hour urine collection time

  • 5-7 days for laboratory analysis and interpretation

  • Results reported to doctor within 7-10 days of starting test

What Do My 5-HIAA Test Results Mean?

  • Normal: Less than 15 mg per 24 hours

  • Elevated: Above 15 mg/24 hrs indicates carcinoid tumor likely

  • Borderline: Levels close to 15 mg may require repeat testing

  • Inconsistent: Multiple collections may be needed to confirm diagnosis

Discuss your individual test results and what they mean for your health with your doctor. If elevated, further imaging tests are done to locate the tumor. Ongoing monitoring of levels helps evaluate treatment effectiveness.

With proper preparation, the 5-HIAA urine test can successfully screen for carcinoid tumors, determine prognosis, and monitor therapy response. Understanding the test and results empowers patients in their cancer care. Speak with your healthcare provider if you have any concerns about having a 5-HIAA test performed.

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