Skip to content

Serum Isoleucine Concentration

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

This test measures the amount of isoleucine, an essential amino acid found in your blood serum. Amino acids like isoleucine play a role in protein synthesis and energy production.

Quick summary

["Isoleucine levels help assess metabolic function and potential amino acid imbalances."]

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

Key facts at a glance

LOINC
47676-2
Short code
Isoleucine SFr DBS
Synonyms
Isoleucine 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 fatigue, muscle weakness, or unexplained weight changes that could be linked to metabolic disorders. It may also be part of a broader evaluation for conditions affecting amino acid metabolism, such as certain genetic disorders or liver/kidney function issues.

What Does the Test Involve?

A blood sample is drawn from a vein, usually in your arm. The sample is sent to a lab where it’s analyzed to measure the concentration of isoleucine. No special preparation is typically needed, but you may be asked to fast for 8–12 hours before the test if instructed by your provider.

What Are Common Causes of Abnormal Results?

Low levels of isoleucine might suggest conditions like amino acid disorders (e.g., maple syrup urine disease), liver disease, or severe malnutrition. High levels could indicate overproduction of amino acids, though this is less common and may require further investigation.

How Are Results Interpreted?

Results are compared to standard reference ranges for healthy individuals. Your healthcare provider will discuss any deviations in the context of your symptoms, medical history, and other test results to determine next steps.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: Isoleucine Levels and Health

Short name

Isoleucine Level

Frequently asked questions

What Might My Results Mean If I Have Symptoms?
If your results are abnormal, it may signal an underlying metabolic issue. For example, persistently low levels could prompt further testing for inherited disorders affecting amino acid metabolism, while unexplained high levels may warrant evaluation for conditions like uncontrolled diabetes or certain liver diseases.
How Often Should This Test Be Done?
The frequency depends on your health status. If this test is part of routine monitoring (e.g., for a known metabolic disorder), your provider will outline a schedule. Otherwise, it may be done only when symptoms or lab findings suggest a need.
Can Diet or Supplements Affect This Test?
Yes. High-protein diets or certain supplements (e.g., branched-chain amino acid supplements) may temporarily alter isoleucine levels. If you’re taking supplements or have dietary restrictions, let your provider know to avoid misleading 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