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Free 3-Methyltyrosine/Creatinine Ratio, 24-Hour Urine

Published: August 9, 2026Updated: August 16, 2026

A 24-hour urine test that measures free 3-methyltyrosine relative to creatinine, a marker associated with catecholamine metabolism.

Quick summary

["This test can help evaluate increased catecholamine production, but results must be interpreted with symptoms, medications, and other tests."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
87498-2
Short code
Free 3-MT/Creat 24h Ur-sRto
Synonyms
Free 3-MT/Creat 24h Ur-sRto
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

What is this test?

This test measures free 3-methyltyrosine, a breakdown product related to catecholamine metabolism, in urine collected over 24 hours. The result is compared with the amount of creatinine in the same collection.

Why might I need this test?

It may be used to help evaluate unexplained episodes of high blood pressure, palpitations, sweating, or headaches that could be related to excess catecholamine production. It is also sometimes used when a tumor that produces catecholamines is suspected.

How is the test performed?

You collect all urine for a full 24-hour period, usually beginning in the morning and ending the following morning. The collection is kept tightly closed, refrigerated if instructed, and returned to the laboratory according to the provided instructions.

How do I prepare for the test?

Follow the laboratory's collection instructions carefully and record when the collection starts and ends. Tell your clinician about medicines, supplements, and foods that may affect the result, because caffeine, nicotine, some medicines, and certain foods can alter catecholamine measurements.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Urinary Free 3-Methyltyrosine

Frequently asked questions

What is free 3-methyltyrosine?
It is a form of 3-methyltyrosine found in urine and is related to the breakdown of catecholamine hormones such as epinephrine and norepinephrine.
Why is creatinine included in the result?
Creatinine provides information about urine concentration and may help evaluate the adequacy of the 24-hour collection. It does not mean that the test is a kidney function test.
Does an abnormal result prove that I have a tumor?
No. An abnormal result can have several causes and must be interpreted with your symptoms, medical history, medications, and other laboratory tests. Your clinician can explain the significance of your result.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy