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Test 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

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

Interpretation

Further clinical investigation (eg, radiographic studies) and genetic studies might be warranted in patients whose 3-methoxytyramine (3MT), metanephrine, or normetanephrine are elevated or when there is a very high clinical index of suspicion.

 

Increased 3MT levels are found in patients with pheochromocytoma and dopamine-secreting tumors.

 

3MT levels of 306 mcg/24 h or less in male patients and 242 mcg/24 h or less in female patients can be detected in non-pheochromocytoma hypertensive patients.

Clinical Reference

1. Muskiet FA, Thomasson CG, Gerding AM, Fremouw-Ottevangers DC, Nagel GT, Wolthers BG. Determination of catecholamines and their 3-O-methylated metabolites in urine by mass fragmentography with use of deuterated internal standards. Clin Chem. 1979;25(3):453-460

2. Taylor RL, Singh RJ: Validation of liquid chromatography-tandem mass spectrometry method for analysis of urinary conjugated metanephrine and normetanephrine for screening of pheochromocytoma. Clin Chem 2002;48:533-539

3. Roden M, Raffesberg W, Raber W, et al. Quantification of unconjugated metanephrines in human plasma without interference by acetaminophen. Clin Chem. 2001;47(6):1061-1067

4. Sawka AM, Singh RJ, Young WF. False positive biochemical testing for pheochromocytoma caused by surreptitious catecholamine addition to urine. The Endocrinologist. 2001;421-423

5. van Duinen N, Steenvoorden D, Kema IP, et al. Increased urinary excretion of 3-methoxytyramine in patients with head and neck paragangliomas. J Clin Endocrinol Metab. 2010;95(1):209-214 doi:10.1210/jc.2009-1632

6. Le Jacques A, Abalain JH, Le Saos F, Carre JL. Interet du dosage urinaire de la 3-methoxytyramine dans le diagnostic des pheochromocytomes et paragangliomes: a propos de 28 cas [Significance of 3-methoxytyramine urine measurement in the diagnosis of pheochromocytomas and paragangliomas: about 28 patients]. Ann Biol Clin (Paris). 2011;69(5):555-559. doi:10.1684/abc.2011.0612

7. Lam L, Woollard, GA Teague L, Davidson, JS. Clinical validation of urine 3-methoxytyramine as a biomarker of neuroblastoma and comparison with other catecholamine-related biomarkers. Ann Clin Biochem. 2017;54(2) 264-272

8. Hirsch, D, Grossman, A, Nadler, V, Alboim, S, Tsvetov, G. Pheochromocytoma: Positive predictive values of mildly elevated urinary fractionated metanephrines in a large cohort of community-dwelling patients. J Clin Hypertens (Greenwich). 2019; 21(10): 1527-1533. doi:10.1111/jch.13657

9. Gupta PK, Marwaha B. Pheochromocytoma. In: StatPearls [Internet]. StatPearls Publishing; 2024. Updated March 5, 2023. Accessed April 22, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK589700

10. Mubarik A, Adeddula NR. Chromaffin Cell Cancer. In: StatPearls [Internet]. StatPearls Publishing; May 8, 2023. Accessed April 22, 2024. Available at www.ncbi.nlm.nih.gov/books/NBK535360/

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. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

82542

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 (h) 13362-9
VL120 Volume (mL) 3167-4