Metanephrines, Fractionated, 24 Hour, Urine
Use
A first- and second-order screening test for the presumptive diagnosis of catecholamine-secreting pheochromocytomas and paragangliomas. It may also be used for confirming positive plasma metanephrine results. This 24-hour urinary fractionated metanephrines assay is more specific than plasma testing and can help reduce unnecessary imaging in low pretest probability settings.
Special Instructions
Patient preparation: discontinue tricyclic antidepressants, labetalol, and sotalol at least one week before collection, if clinically feasible. Requisition forms include Oncology Test Request (T729) or Renal Diagnostics Test Request (T830). Add preservative at start of collection: 10 g boric acid (3 g pediatric) or 25 mL 50% acetic acid (15 mL pediatric).
Limitations
This LC‑MS/MS method is not affected by interferences such as diatrizoate, chlorpromazine, hydrazine derivatives, imipramine, MAO inhibitors, methyldopa, phenacetin, ephedrine, or epinephrine, nor by acetaminophen as seen with older plasma HPLC methods. Complete 24‑hour collections are necessary, especially in episodic hypertension; incomplete or improper collections may compromise interpretation.
New York Approved
Methodology
Mass Spectrometry (LC-MS/MS)
Biomarkers
LOINC Codes
- 2608-8
Result Turnaround Time
3-5 days
Related Documents
For more information, please review the documents below
Specimen
Urine
Volume
10 mL
Minimum Volume
3 mL
Container
Plastic urine tube
Collection Instructions
Add 10 g boric acid (3 g pediatric) or 25 mL 50% acetic acid (15 mL pediatric) as preservative at start of 24‑hour collection. Collect urine for 24 hours.
Patient Preparation
Discontinue tricyclic antidepressants, labetalol, and sotalol at least one week before collection, if clinically feasible.
Storage Instructions
Refrigerated preferred; ambient and frozen acceptable for up to 28 days.
Causes for Rejection
Specimens with collection intervals less than 22 hours or more than 26 hours or incomplete collections are unacceptable; all specimens evaluated for suitability.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 28 days |
| Refrigerated | 28 days |
| Frozen | 28 days |