Test Directory

Specimen Type: 24 Hour Urine

Collection Container: 24 Hour Plastic Urine Container

Desired Specimen Volume: 4 mL

1. Collect 24-hour urine in a timed collection jug.
2. Refrigerate during 24-hour collection.

1. Record total volume and collection time interval on transport tube and test request form 
2. Transfer 4 mL of urine from a well-mixed 24-hour collection to a clear aliquot tube (screw cap).

Avoid bananas, avocados, plums, eggplant, tomatoes, avocados plums, eggplant, tomatoes, plantain, pineapple, walnuts, and interfering drugs for a 72 hour period prior to and during collection. Foods and medications associated with altered urinary HIAA results: Decreased HIAA: Aspirin, chlorpromazine (Thorazine), corticotropin, dihydroxyphenylacetic acid, alcohol, gentisic acid, homogentisic acid, hydrazine derivatives, imipramine (Tofranil®), <isocarboxazid (Marplan), keto acids, levodopa, MAO inhibitors, methenamine methyldopa (Aldomet®), perchlorperazine, phenothiazines (Compazine®), promazine, promethazine (Mepergan®). Increased HIAA: Acetaminophen, acetanilide, caffeine, coumaric acid, diazepam (Valium®), ephedrine, fluorouracil glycerol guaiacolate (Guaifenesin), melphalan (Alkeran®), mephenesin, methamphetamine (Desoxyn), methocarbamol (Robaxin®), naproxen, nicotine, phenacetin, phenmetrazine, phenobarbital, phentolamine, rauwolfia, reserpine.

Transport to the laboratory refrigerated. 

• pH <2

See patient report.

Levels of 5-HIAA may not be elevated in nonfunctional tumors. Because flushing is mediated by different hormones in foregut and midgut tumors, some patients with a neuroendocrine tumors will have symptoms of flushing with low or normal levels of 5-HIAA. A number of substances interfere with determination of urinary 5-HIAA.1

Causes of Elevated 5-HIAA:

• Foods: Avocado, bananas, eggplant, kiwi fruit, nuts (hickory nuts, pecans, walnuts), pineapple, plums, tomato products.

• Drugs: Acetaminophen (Tylenol®), antihistamines (nasal drops and spray), antihypertensives, antipsychotics, caffeine, cough suppressants, diazepam (Valium®), muscle relaxants, nicotine, warfarin (Coumadin®)

Causes of Diminished 5-HIAA:

• Alcohol, aspirin, antidepressants (imipramine, monoamine oxidase inhibitors), herbal products: Diadzin (active compound in kudzu, a Chinese herbal treatment for alcohol abuse), St John's wort

• 5-HIAA, Quantitative, 24-Hour Urine
• Serotonin Metabolite, 24-Hour Urine