Serum or plasma leucine concentration
This test measures the amount of leucine, an essential amino acid, in your blood. Leucine plays a role in protein synthesis and muscle repair.
["Leucine levels help assess protein metabolism and may be checked in conditions affecting muscle or metabolism."]
Key facts at a glance
- LOINC
- 26710-4
- Short code
- Leucine Amn-sCnc
- Synonyms
- Leucine Amn-sCnc
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 2-5 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h
- Hemolysis max
- 300
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order this test if you have symptoms like muscle weakness, fatigue, or unexplained weight changes. It could also be part of a broader evaluation for metabolic disorders, liver disease, or kidney problems. Rarely, it may be used to monitor treatment for conditions like phenylketonuria or certain genetic disorders.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it’s part of a metabolic panel. Avoid excessive alcohol or strenuous activity the day before. If you’re on medications, check with your provider to confirm if you should stop or adjust doses temporarily.
What the Test Involves
A healthcare professional will draw blood from a vein in your arm using a small needle. You may feel a slight pinch, but the process is quick. The blood sample is then sent to a lab for analysis.
What the Results Mean
Results are typically reported as a mass concentration (e.g., in micromoles per liter). While reference ranges vary by lab, abnormal levels may signal conditions like liver disease, kidney dysfunction, or certain metabolic disorders. Your provider will interpret the results in the context of your overall health and symptoms.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated leucine levels may indicate liver disease, kidney failure, or conditions that disrupt protein metabolism. Low levels are less common but could occur in severe malnutrition or certain genetic disorders. Leucine is also a key stimulator of muscle protein synthesis, so monitoring its levels may be relevant in patients undergoing muscle recovery or those with chronic illnesses affecting metabolism.
Short name
Leucine Level
Frequently asked questions
How long does it take to get results?
What causes leucine levels to change?
Can lifestyle changes affect leucine levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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