Overview
Neuroendocrine Tumours (NETs) may produce excessive amounts of serotonin, causing symptoms such as facial flushing, diarrhoea and/or wheezing. Your doctor may request a 24-hour 5HIAA urine test if it is suspected you have a serotonin-producing NET or if you have these symptoms.
5-hydroxyindoleacetic acid (5-HIAA) is the primary breakdown product of serotonin, a chemical substance that transmits messages between nerve cells. Serotonin assists with regulating the digestive tract, influencing gut motility and function, blood vessel constriction, the wake–sleep cycle, and a person’s mood.
Discuss with your doctor
Some medications interfere with the measurement of 5-HIAA.
If you are taking any of the following:
- Medications, including non-prescription or over-the-counter medicines and cough syrups
- Nutritional supplements
- Complementary medicines
Please check with your doctor to determine if any need to be temporarily withheld or changed to alternatives before the test. In particular, medications used for treatment of depression, psychosis, anxiety, nausea, and migraines might affect your test result.
DO NOT STOP ANY MEDICATIONS UNLESS INSTRUCTED TO DO SO BY A MEDICAL PROFESSIONAL.
For 48 HOURS (2 days) BEFORE AND DURING the urine collection of a 24-hour urine specimen, DO NOT eat the following foods or any food or drinks containing:
Fruit:
- Bananas
- Kiwifruit
- Pineapple
- Plums
- Passionfruit
- Grapes
Vegetables
- Avocado
- Tomatoes (including in sauces and soups)
Nuts
- All nuts
- Nut containing products (including peanut butter, biscuits, cereals, and snacks containing nuts)
Supplements
- Supplmenets containing serotonin
For 24 HOURS (1 day) BEFORE AND DURING the urine collection of a 24-hour urine specimen, DO NOT drink beverages or eat foods containing alcohol.
Foods you can eat
- Fresh milk (cows, coconut, soy, oat), plain or vanilla yoghurt (no added fruit), mayonnaise, cream, sour cream, butter and margarine, oil for cooking (except peanut oil)
- White/brown bread/toast, cereal without nuts, eggs, white/brown rice, potatoes, rice noodles
- Pasta: Including spaghetti or noodles. Avoid those containing nuts, seeds, fruit, flavouring or fillings as listed above, e.g., avoid ravioli and coloured pastas
- Rice crackers (plain), flour, sugar
- Protein: meat, chicken, fish, eggs
- Cheese: cream cheese, cheddar, ricotta, feta, cottage, mozzarella, parmesan
- White chocolate, vanilla ice cream, custard
- Fresh/tinned/frozen fruit: apples, pears, apricots, peaches, rockmelon, watermelon, berries
- FLUIDS are allowed: water, soda water, mineral water, cordial, sports drinks, soup (e.g., chicken broth, pumpkin soup, etc.)
Sample menu plan
| Meal | Allowed | Not Allowed |
|---|---|---|
| Breakfast |
|
• Almond milk • Avocados, tomatoes • Bread and cereal containing nuts • Banana bread • Spreads containing nuts, plum, passionfruit, kiwifruit or pineapple jams, eggplant, avocado or tomato-based spreads |
| Morning Tea | • Water or mineral water • Fruit bowl with watermelon, blueberries, oranges, honeydew, papayas or strawberries • Yogurt with strawberries and blueberries • Juices including bananas, plums, passionfruit, grapes, kiwifruit or pineapple |
• Tea, coffee and alcohol • Other caffeinated beverages (e.g. certain energy drinks) |
| Lunch | • White / brown bread sandwich with sliced chicken breast (not processed meat), lettuce, cucumber • Chicken breast salad (Kale, cucumber, lettuce, carrots, beetroot) |
• Salads containing tomato, eggplant, avocado or plantain |
| Afternoon Tea | • Plain vanilla yoghurt • Cheese with rice cakes |
• Biscuits containing nuts • Milk or milk-alternative drinks containing banana or coffee • Soft and semi-soft cheese containing nuts |
| Dinner | • White fish or chicken fillet, mash potatoes or rice • Steak and steamed vegetable (carrots, corn, peas, capsicum) with rice • Chicken soup (clear broth) with rice noodles, sliced chicken breast and green vegetables • Pasta, white sauce, chicken breast and parmesan cheese |
• Eggplant, tomatoes, avocados • Soups containing eggplant, tomato or avocado • Rice/Pasta Plantain • No pickled vegetables |
| Desserts | • Ice-cream • Jelly • Custard |
• Desserts containing bananas, plums, passionfruit, grapes, kiwifruit, pineapple, nuts • Coffee-flavoured desserts • Desserts with alcohol as an ingredient |
If you require further guidance on how to complete your test collection, please refer to the evidence-based 5-HIAA urine collection guide developed by the Harmonisation of Endocrine Dynamic Testing – Adult (HEDTA) group:
