5-HIAA (5-Hydroxyindoleacetic Acid), 24-Hour Urine

Test Code
39625X

Components
Includes creatinine.

CPT Codes
83497; 82570

Specimen Container
24-hour urine container-25 mL 6N HCl

Preferred Specimen
10 mL urine (5 mL minimum).

Instructions
Collect 24-hour urine with 15 g of boric acid or 25 mL of 6N HCl to maintain a pH below 3. Urine without preservative is acceptable if pH is below 6 and the sample is shipped frozen. Keep urine refrigerated during collection if preservative is not used. Record 24-hour urine volume on test request form and urine vial. Record patient's age on test request form and urine vial. Patient should avoid food high in indoles: avocado, banana, tomato, plum, walnut, pineapple, and eggplant. Patient should also avoid tobacco, tea and coffee for three days prior to specimen collection.

Transport Temperature
Room temperature

Methodology
High Performance Liquid Chromatography, Electrochemical Detection

Reference Range

0 - 1 years:	not established
2 - 10 years:	8.0 or less mg/24 hr
>10 years:	6.0 or less mg/24 hr

Clinical Use
5-HIAA is the end product of serotonin (5-hydroxytryptophan) and tyrptophan metabolism. Patients with carcinoid tumors of the midgut, e.g., ileum, produce high concentrations of 5-HIAA. Patients with carcinoid tumors of the foregut and hindgut may produce little or no 5-HIAA or do so intermittently.

Performed By
Quest Diagnostics Nichols Institute