5-HIAA (5-Hydroxyindoleacetic Acid), 24-Hour Urine [523X]

Test Code
523X

Preferred Specimen
10 mL of 24-hour urine with 25 mL 6N HCl collected in a 24-hour urine container

Minimum Volume
5 mL

Other Acceptable Specimens
Unpreserved 24-hour urine with pH <6

Instructions
Collect 24-hour urine with 25 mL of 6N HCl to maintain a pH <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 patients age on test request form and urine vial.

Transport Temperature
Preserved urine: Room temperature
Unpreserved urine: Frozen

Specimen Stability
Room temperature: 7 days
Refrigerated: 30 days
Frozen: 30 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
pH >3.0 • Received unfrozen

Methodology
High Performance Liquid Chromatography (HPLC)

This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by the FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Limitations
Requires accurate 24-hour urine collection. Patients with renal disease may display falsely decreased results. Urinary 5-HIAA is increased in patients with malabsorption disorders who also display a larger concentration of urinary tryptophan metabolites. Urinary 5-HIAA is increased in patients with intestinal obstruction and with some noncarcinoid islet cell tumors. Carcinoid syndrome may not cause elevated results, especially if the patient does not have diarrhea.

Reference Range
2-10 Years ≤8.0 mg/24 h
>10 Years ≤6.0 mg/24 h


Clinical Significance
Values above 10 mg/24-hours occur in carcinoid syndrome. Slight elevations also occur in nontropical sprue and after reserpine administration.
Drugs which can interfere with testing due to physiologic response: Acetaminophen, alpha and beta blockers, atenolol, bromocriptine, broncholdilators, clonidine, digoxin, isoniazid, L-dopa, labetelol, methyldopa, monoamine oxidase inhibitors, nitroglycerin, sympathomimetic amines, phenobarbital, phenothiazines, phentolamine, reserpine, salicylates, tricyclic antidepressants.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153



The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.