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Serum Leucine Concentration (Mass Concentration)

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

This test measures the amount of the amino acid leucine in your blood serum. Leucine is one of the essential amino acids needed for muscle repair and protein synthesis.

Quick summary

["Leucine levels can help assess metabolic health or be checked if you have conditions affecting protein metabolism."]

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

Key facts at a glance

LOINC
47680-4
Short code
Leucine SFr Hair
Synonyms
Leucine SFr Hair
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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 recommend this test if you have symptoms of metabolic disorders, such as muscle weakness, fatigue, or unexplained weight changes. It could also be part of a broader evaluation for conditions like liver disease, kidney problems, or certain genetic disorders that affect amino acid metabolism.

What to Expect Before the Test

No special preparation is typically required, but you may be asked to fast for a few hours before the blood draw. Wear a loose shirt for easy access to your arm.

What Happens During the Test

A healthcare professional will insert a small needle into a vein in your arm to collect a blood sample. You may feel a slight pinch, but the procedure usually takes just a few minutes.

What the Results Mean

Results are compared to a general reference range for healthy individuals. Abnormal levels might suggest issues like hyperaminoacidemia, liver or kidney disease, or other metabolic conditions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Serum Leucine

Frequently asked questions

What causes leucine levels to be tested?
Leucine levels may be checked if you have symptoms like unexplained muscle weakness, fatigue, or signs of metabolic disorders. It could also be part of a diagnostic workup for conditions affecting protein metabolism, liver or kidney function, or genetic disorders.
What does it mean if my leucine level is high?
High leucine levels may suggest metabolic issues, such as hyperaminoacidemia, or conditions like liver disease or kidney problems. Your provider will review your full clinical picture to determine the cause and next steps.
Do I need to prepare for this test?
No specific preparation is usually needed, but you may be asked to fast for a few hours before the blood draw to ensure accurate results.
  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