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5-Hydroxyindoleacetic Acid (5-HIAA), 24-Hour Urine, with Creatinine
Test Code39625
CPT Codes
83497, 82570
Includes
CPT code 81050 may be added at an additional charge for volume measurement
Preferred Specimen
10 mL aliquot from a 24-hour urine that has been preserved with 25 mL 6N HCl, collected in a plastic 24-hour urine container
Patient Preparation
Patient should avoid food high in indoles: avocado, banana, tomato, plum, walnut, pineapple, and eggplant
Minimum Volume
5 mL
Other Acceptable Specimens
Aliquot from a 24-hour urine, unpreserved with a pH ≤6, collected in a plastic 24-hour urine container
Instructions
Collect 24-hour urine with 25 mL 6N HCl to maintain a pH ≤3. If no preservative is used, specimen must be stored refrigerated during collection but shipped frozen and pH must be ≤6.
Record 24-hour urine volume and patient's age on test request form and urine container.
Transport Temperature
Preserved urine: Room temperature
Unpreserved urine: Frozen
Unpreserved urine: Frozen
Specimen Stability
Preserved urine
Room temperature: 7 days
Refrigerated: 30 days
Frozen: 30 days
Unpreserved urine
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days
Room temperature: 7 days
Refrigerated: 30 days
Frozen: 30 days
Unpreserved urine
Room temperature: Unacceptable
Refrigerated: Unacceptable
Frozen: 30 days
Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Preserved urine received refrigerated with a pH >3 • Unpreserved urine received frozen with pH >6
Methodology
High Performance Liquid Chromatography (HPLC) • Electrochemical Detection
FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.
Setup Schedule
Tue, Thu-Fri
Report Available
3 to 7 Day(s)
Limitations
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.
Clinical Significance
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.