24-Hour Urine Collection Instructions for Your 5-Hydroxyindoleacetic Acid (5-HIAA) Test

Share
Time to Read: About 3 minutes

This information explains how to collect and store your urine (pee) so it can be tested for 5-hydroxyindoleacetic acid (5-hy-DROK-see-IN-dole-uh-SEE-tik A-sid), or 5-HIAA.

About your 5-HIAA test

5-HIAA is made when your body breaks down serotonin (SAYR-uh-TOH-nin). Serotonin is a chemical. Nerves in your brain and body use serotonin to send messages to one another. Some types of tumors also release serotonin.

Your kidneys filter 5-HIAA from your blood. Your urine carries it out of your body. By measuring the amount of 5-HIAA in your urine, we can tell how much serotonin is in your body.

‌  It’s important to collect all your urine for the whole 24-hour collection period. If you do not collect all your urine, we may not be able to complete this laboratory test.

Things to avoid before and during your 24-hour urine collection

Some things can make your test results less accurate. It’s best to avoid these things starting 3 days before your urine collection. Keep avoiding them during your 24-hour urine collection.

Foods and drinks to avoid

  • Foods and drinks with caffeine, such as coffee, tea, energy drinks, and chocolate.
  • Bananas and plantains.
  • Pineapple and pineapple juice.
  • Plums.
  • Tomatoes and tomato products.
  • Kiwis.
  • Avocados.
  • Eggplant.
  • Nuts.
  • Squash, including winter squashes (such as butternut squash) and summer squashes (such as zucchini).

Medicines to avoid

Make sure your healthcare provider knows all the prescription and over-the-counter medicines you take.

If you take any of the medicines below, they may tell you to stop before and during your 24-hour urine collection. Do not stop taking any medicines unless your healthcare provider tells you to.

  • Acetaminophen (Tylenol®).
  • Cough suppressants, such as guaifenesin (Mucinex®) and dextromethorphan (Delsym®, Robitussin®).
  • Aspirin.
  • Antihistamines (allergy medicines), such as cetirizine (Zyrtec®), loratadine (Claritin®), fexofenadine (Allegra®), and diphenhydramine (Benadryl®).
  • Methocarbamol (Robaxin®).
  • Levodopa (Inbrija®).
  • Monoamine oxidase inhibitors (MAOIs).
  • Tricyclic antidepressants.
  • Methyldopa.

Other things to avoid

  • Products with nicotine, such as:
    • Cigarettes and other tobacco products.
    • Vapes and e-cigarettes.
    • Nicotine patches.
    • Nicotine pouches.

Talk with your healthcare provider if you do not think you can stop using nicotine during your 24-hour urine collection. 

Instructions for your urine collection

We will give you the following supplies. We may give them to you during an appointment or mail them to you.

  • A plastic container to collect your urine.
    • If you’re male, we will give you a handheld urinal.
    • If you’re female, we will give you a urine collection “hat.”
    • If you’re staying in the hospital, we may give you a bedpan.
  • A plastic container to store your urine. Write your name on the label.

Starting your 24-hour urine collection period

You must start your urine collection period with an empty bladder. Right before you start the 24-hour collection period, urinate (pee) into the toilet and flush it. Then, write down the time and date. This is the start time of your urine collection period. It will end 24 hours later.

During your 24-hour urine collection period

  • Collect all of your urine. Only urinate into the urinal, collection hat, or bedpan.
    • To use the urine collection hat, place it under the toilet seat and urinate into it.
    • If you’re staying in the hospital, ask for help if you need it.
  • Do not put toilet paper in the urinal, collection hat, or bedpan. Put it in the toilet and flush it.
  • Each time you urinate, pour the urine from the urinal or collection hat into the labeled container. If you’re using a bedpan, ask your nurse or nursing assistant to do this for you.
  • Plan ahead if you leave your home or hospital room during your 24-hour collection period. Take the urinal or collection hat and labeled container with you.
  • Make sure to drink at least 8 (8-ounce) cups of liquids during your 24-hour collection period. If you’re staying in the hospital, you may also get fluids intravenously (through a vein).

Store the labeled container in the refrigerator. The urine must be kept cool at all times. If you do not have space in the refrigerator, you can store it in a cooler on top of ice. Add more ice as needed to keep the urine cold.

Ending your 24-hour urine collection period

Your last urine collection should be within 10 minutes before or after the time you started your urine collection period.

For example, if you urinated at to start your urine collection period, try to collect your urine between and the next day. This will end your urine collection period.

After your 24-hour urine collection period

If you collected your urine while you were at home:

  • You’ll have an appointment within 24 hours after your urine collection period ends. Bring your labeled urine container to your appointment.
  • Tell your nurse if you forgot to save any of your urine during the collection period.

If you collected your urine while you were in the hospital:

  • A nurse or nursing assistant will collect your labeled urine container.
  • Tell your nurse or nursing assistant if you forgot to save any of your urine during the collection period.

Last Updated

Thursday, April 18, 2024

Tell us what you think

Tell us what you think

Your feedback will help us improve the educational information we provide. Your care team cannot see anything you write on this feedback form. Please do not use it to ask about your care. If you have questions about your care, contact your healthcare provider.

While we read all feedback, we cannot answer any questions. Please do not write your name or any personal information on this feedback form.

Questions Yes Somewhat No
Please do not write your name or any personal information.