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Serum/Plasma Free Tyrosine Concentration (Mass Concentration)

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

This test measures the amount of the amino acid tyrosine in your blood, which can help assess metabolic function or identify certain genetic conditions.

Quick summary

["Tyrosine is an essential amino acid involved in brain development and hormone production."]

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

Key facts at a glance

LOINC
11816-6
Short code
Fet Yolk sac Diam US.meas
Synonyms
Fet Yolk sac Diam US.meas
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
us-measured
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may request this test if you have symptoms like fatigue, weight changes, or signs of metabolic disorders. It could also be part of a broader evaluation for conditions like phenylketonuria (PKU) or other amino acid imbalances.

What to Expect Before the Test

No special preparation is needed. You may have a small needle inserted into your arm to draw blood. If you’re taking medications that affect amino acids, let your provider know.

What the Results Mean

Results are not typically provided as a single reference range since tyrosine levels can vary based on diet, health status, and other factors. Your provider will interpret the result in the context of your overall health and symptoms.

Common Conditions Monitored

This test may be used to monitor conditions like PKU, where tyrosine levels are critical. It can also help diagnose or manage metabolic disorders affecting amino acid metabolism.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal tyrosine levels may indicate metabolic disorders, genetic conditions, or other health issues affecting amino acid metabolism. Your provider will use the result alongside other tests and symptoms to guide diagnosis and treatment.

Short name

Free Tyrosine Level

Frequently asked questions

What causes tyrosine levels to be tested?
Your doctor may order this test if you have symptoms like unexplained fatigue, developmental delays in children, or if they suspect a metabolic disorder related to amino acids.
How is this test different from other amino acid tests?
Unlike tests for specific amino acids like phenylalanine, this test measures free tyrosine concentration in your blood, which can help assess broader metabolic function.
Can diet affect tyrosine test results?
Yes, diet can influence tyrosine levels. High-protein diets or certain medical conditions may temporarily alter results, so your provider will consider overall health context when interpreting the test.
  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