Metanephrines, Fractionated, Quantitative, 24-Hour Urine
Use
Evaluation of catecholamine-secreting tumors of the adrenal medulla (pheochromocytomas) and extra-adrenal sympathetic and parasympathetic paragangliomas.
Special Instructions
Ensure the total 24-hour urine volume is recorded on the request form. Patients should avoid caffeine before and during the collection and discontinue monamine oxidase inhibitors at least one week prior to the collection.
Limitations
The low prevalence of pheochromocytomas and paragangliomas (PPGL) and the limited diagnostic specificity of metanephrine tests can result in many false-positive results compared to true-positive ones. Medications such as antidepressants, alpha and beta blockers, caffeine, smoking, and physical exercise can also cause borderline elevation, leading to potential false positives. Guidelines recommend careful clinical evaluation to confirm true positive results and appropriate follow-up with imaging or additional testing based on the results and clinical context.
Methodology
Mass Spectrometry
Biomarkers
LOINC Codes
- 101400-0
- 21422-1
- 2671-6
- 21019-5
- 19049-6
Result Turnaround Time
3-6 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
10 mL aliquot
Minimum Volume
2.5 mL aliquot
Container
Plastic urine container with no preservative or 6N HCl
Collection Instructions
Instruct patients to void at 8 AM, discard the specimen, then collect all urine including the final specimen voided at the end of the 24-hour collection period (8 AM the next morning). Measure and record total 24-hour volume. Mix well and send aliquot.
Patient Preparation
No caffeine before or during collection. Monamine oxidase inhibitors should be discontinued at least one week prior to beginning collection.
Storage Instructions
Store at room temperature.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |