5-Hydroxyindoleacetic Acid Urine
(5-HIAA)

Sample type: -

Urine (24-hour)

Uses: -

Helps diagnose and monitor treatment for serotonin-secreting carcinoid tumors.

Precautions: -

Do not allow the patient to eat any bananas, pineapple, tomatoes, eggplants, plums, or avocados for 48 hours before or during the 24-hour test because these foods contain serotonin.

Interfere action: -

1- False-positive results occur with

a) Ingestion of banana, pineapple, plum, walnut, eggplant, tomato, chocolate, and avocado, because of their serotonin content.

b) Many drugs: acetaminophen (Tylenol), antihistamines (nasal drops and spray), antihypertensives, antipsychotics, caffeine, cough suppressants, diazepam (Valium), muscle relaxants, nicotine, warfarin (Coumadin).

c) After surgery (surgical stress).

2- False-negative results can be caused by specific drugs that depress 5-HIAA production.

Pre analytical error: -

• When collecting specimens in an unsterile cup, the sample becomes contaminated, leading to an incorrect result.

• If the container that the patient collects the urine in it unlabeled with his name and date and the time that he collects the urine during it.

Corrective action: -

• The sample must be rejected, and another sample obtained because the sample should be collected in sterile cup.

• If the patient forgets the date and time, you should reject this sample and ask about another one. But if he knows the date and time, you can let him label the container with this information.

Post analytical error: -

• Reports were sent to the incorrect patient.

Corrective action: -

• Communication with patient, apologizing for the error, and providing him with the correct report.

Reference range: -

• Qualitative: Negative

• Quantitative: 2–7 mg/24 hours or 11–37 µmol/day