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Serum Leucine Concentration (Mass Concentration)

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

This test measures the amount of leucine, an essential amino acid, in your blood serum. Leucine plays a role in protein synthesis and muscle metabolism.

Quick summary

["Leucine levels help assess metabolic or muscle-related conditions."]

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

Key facts at a glance

LOINC
47683-8
Short code
Leucine SFr SerPl
Synonyms
Leucine SFr SerPl
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 Is This Test Done?

Your healthcare provider may order this test if you have symptoms like muscle weakness, fatigue, or unexplained weight changes. It can also be part of evaluations for metabolic disorders, liver disease, or kidney function.

What to Expect Before the Test

No special preparation is typically needed, but you may be asked to fast for a few hours before the blood draw if your provider specifies it. Bring any medications or supplements you’re currently taking.

What Happens During the Test?

A healthcare professional will draw blood from a vein in your arm. You may feel a slight pinch, but it usually doesn’t cause significant discomfort. The blood sample is then sent to a lab for analysis.

What Do Results Mean?

Results are compared to standard reference ranges for healthy adults. Abnormal levels may indicate conditions like hyperaminoaciduria (excess amino acids in urine), liver disease, or certain metabolic syndromes.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Leucine Level

Frequently asked questions

How often should leucine levels be checked?
Leucine levels are generally not a routine screening test. Your provider may recommend it if you have symptoms or conditions linked to amino acid imbalances, such as liver disease, kidney problems, or unexplained muscle weakness.
What causes leucine levels to change?
Several factors can influence leucine levels, including diet (especially high-protein foods), liver or kidney function, certain medications, or metabolic disorders. Stress, illness, or rapid weight changes may also affect results.
Can lifestyle changes impact leucine levels?
Yes, diet plays a role. Reducing high-protein foods or consulting a dietitian may help stabilize levels if they’re elevated. However, lifestyle changes alone won’t replace medical evaluation for underlying conditions.
  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