5-HIAA tests


5-HIAA tests

Hydroxyindoleacetic acid (5-HIAA) is a breakdown product of the hormone serotonin, which NETs can release. Since serotonin levels go up and down throughout a typical day, a 24-hour urine collection of the 5-HIAA byproduct is more reliable in measuring the daily amounts of the hormone.

Some centers now have the capability of doing this test with a blood sample,
eliminating the need to collect urine. Your doctor may use the 5-HIAA test in diagnosing and monitoring some neuroendocrine cancer.


The following are some food items to be avoided for 48 hours before a 5-HIAA test:

  • Avocados
  • Bananas
  • Cantaloupe
  • Eggplant
  • Grapefruit
  • Dates
  • Hickory nuts


  • Honeydew melon
  • Kiwi
  • Pecans
  • Pineapple
  • Plantains
  • Plums
  • Tomatoes and tomato products Walnuts

Other items may also affect your test results. Before starting your urine test, be sure to ask your doctor for a complete list of the foods and medications you need to avoid.

Diagnostic Tests

Testing can help your doctor understand the specifics of your tumor and develop a treatment plan for your neuroendocrine cancer.