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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 amino acid metabolism and potential metabolic disorders."]

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

Key facts at a glance

LOINC
47684-6
Short code
Leucine SFr DBS
Synonyms
Leucine SFr DBS
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 that could suggest metabolic issues. It may also be part of a broader evaluation for conditions like liver disease, kidney problems, or certain genetic disorders affecting amino acid metabolism.

What to Expect Before the Test

No special preparation is usually needed. You may be asked to fast for 8–12 hours before the test if instructed by your provider. Bring any medications you’re taking to your appointment.

How the Test Is Performed

A healthcare professional will draw blood from a vein in your arm using a needle. The blood sample is then sent to a lab for analysis using a high-performance liquid chromatography (HPLC) method to measure leucine concentration.

What the Results Mean

Results are typically reported in milligrams per deciliter (mg/dL) or micromoles per liter (µmol/L). While reference ranges vary by lab, abnormal levels may indicate conditions affecting amino acid metabolism, such as hyperleucinemia or inherited disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Leucine Level

Frequently asked questions

What Are Common Causes of Abnormal Results?
Abnormally high leucine levels may be linked to liver disease, kidney dysfunction, or certain genetic disorders like maple syrup urine disease. Low levels are less common but could result from severe malnutrition or metabolic disorders.
How Might My Doctor Use These Results?
Your doctor may use these results to diagnose or monitor conditions affecting amino acid metabolism, guide treatment plans, or assess how well your body processes nutrients.
Is This Test Painful or Discomforting?
The blood draw may cause a slight sting or bruising, but most people experience minimal discomfort. You can resume normal activities immediately after the procedure.
  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