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Order Code 3MT 3-Methoxytyramine, 24 Hour, Urine


Necessary Information


24-Hour volume (in milliliters) 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. 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.

3.Collect urine for 24 hours.. 

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


Useful For

A first- and second-tier 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

Urine

Specimen Minimum Volume

3 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 28 days
  Frozen  28 days
  Ambient  21 days

Reject Due To

Gross hemolysis OK
Gross icterus OK

Reference Values

Males: ≤306 mcg/24 h

 

Females: ≤242 mcg/24 h

 

For International System of Units (SI) conversion for Reference Values, see www.mayocliniclabs.com/order-tests/si-unit-conversion.html

Method Description

Urinary 3-methoxytyramine is determined by reverse-phase liquid chromatography tandem mass spectrometry with stable isotope dilution analysis.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Performing Laboratory

Mayo Clinic Laboratories in Rochester

CPT Code Information

82542

Urine Preservative Collection Options

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

Ambient (no additive)

OK

Refrigerate (no additive)

OK

Frozen (no additive)

OK

50% Acetic Acid

Preferred

Boric Acid

Preferred

Diazolidinyl Urea

No

6M Hydrochloric Acid

OK

6M Nitric Acid

No

Sodium Carbonate

OK

Thymol

No

Toluene

OK