Ordering Guidance

This test quantifies 5-hydroxyindoleacetic acid in plasma specimens and is comparable to testing on 24-hour and random urine specimens for the diagnosis and monitoring of intestinal carcinoid syndrome.

Necessary Information

Patient's age is required.

Specimen Required

Patient Preparation:

1. Some medications could interfere with test results. The ordering provider should decide if any medications should be stopped and when they should be restarted. If clinically feasible, discontinue the following medications at least 24 hours prior to specimen collection:

-Acetaminophen (Tylenol or generic versions)

-Tryptophan containing supplements.

2. For 24 hours prior to the collection, the patient should:

Limit the following to one serving per day:

-Fruits

-Vegetables

-Caffeinated beverages or foods

Abstain from the following:

-Nuts, especially walnuts. Plasma 5-hydroxyindoleacetic acid levels revert to baseline levels when walnuts are ingested after other foods.

Collection Container/Tube:

Preferred: Green top (sodium heparin)

Acceptable: Lavender top (EDTA)

Submission Container/Tube: Plastic vial

Specimen Volume: 0.5 mL

Collection Instructions:

1. Centrifuge at 4° C.

2. Aliquot plasma into plastic vial.

3. Send plasma frozen.