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Test ID 3MT 3-Methoxytyramine, 24 Hour, Urine

Necessary Information

24-Hour volume is required.

Specimen Required

Patient Preparation: Tricyclic antidepressants, labetalol, and sotalol medications may elevate levels of catecholamines producing results that cannot be interpreted. If clinically feasible, it is optimal to discontinue these medications at least 1 week before collection. Levodopa (Sinemet) medication will cause false-positive results. For advice on assessing the risk of removing patients from these medications and alternatives, consider consultation with a specialist in endocrinology or hypertension.

Supplies: Urine Tubes, 10 mL (T068)

Submission Container/Tube: Plastic urine tube

Specimen Volume: 10 mL

Collection Instructions:

1. Complete 24-hour urine collections are preferred, especially for patients with episodic hypertension; ideally the collection should begin at the onset of a "spell."

2. Collect urine for 24 hours.

3. Add 10 g (pediatric: 3 g) of boric acid or 25 mL (pediatric: 15 mL) of 50% acetic acid as preservative at start of collection.

Additional Information: See Urine Preservatives-Collection and Transportation for 24-Hour Urine Specimens for multiple collections.

Useful For

A first- and second-order screening test for the presumptive diagnosis of catecholamine-secreting pheochromocytomas and paragangliomas


Testing in conjunction or as an alternative to plasma metanephrines (PMET / Metanephrines, Fractionated, Free, Plasma) or plasma catecholamine (CATP / Catecholamine Fractionation, Free, Plasma) testing

Method Name

Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Reporting Name

3-Methoxytyramine, 24h, U

Specimen Type


Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  90 days
  Ambient  28 days

Reference Values

Males: ≤306 mcg/24 hours

Females: ≤242 mcg/24 hours

Day(s) Performed

Monday through Friday

Report Available

3 to 5 days

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed, and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
3MT 3-Methoxytyramine, 24h, U 32618-1


Result ID Test Result Name Result LOINC Value
65157 3-Methoxytyramine, U 32618-1
TM120 Collection Duration 13362-9
VL120 Urine Volume 3167-4

Urine Preservative Collection Options

Note: The addition of preservative must occur prior to beginning the collection.







50% Acetic Acid


Boric Acid


Diazolidinyl Urea


6M Hydrochloric Acid


6M Nitric Acid


Sodium Carbonate