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Serum Isoleucine Concentration (Mass Concentration)

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

This test measures the amount of the amino acid isoleucine in your blood serum. Amino acids are building blocks of proteins and play key roles in metabolism.

Quick summary

["Isoleucine levels help assess protein metabolism and potential amino acid imbalances."]

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

Key facts at a glance

LOINC
47675-4
Short code
Isoleucine SFr SerPl
Synonyms
Isoleucine 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 This Test Might Be Ordered

Your healthcare provider may order this test if you have symptoms like muscle weakness, fatigue, or unexplained weight changes that could suggest 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 disease.

What to Expect Before the Test

No special preparation is usually needed. You may have blood drawn from a vein in your arm, similar to other blood tests. If you’re on a special diet or medication, let your provider know beforehand.

What the Results Mean

Results are compared to a reference range for healthy adults, though exact values can vary by lab. Abnormal results may indicate conditions like aminoacidopathies, liver disease, or malnutrition. Your provider will discuss findings in the context of your overall health.

Common Conditions Linked to Isoleucine Levels

Elevated levels might be seen in liver disease or certain metabolic disorders, while low levels could suggest malnutrition, kidney disease, or conditions affecting protein breakdown.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Isoleucine Level

Frequently asked questions

What causes isoleucine levels to be checked?
Your doctor may order this test if you have symptoms like unexplained fatigue, muscle weakness, or changes in appetite. It may also be part of routine monitoring for people with known metabolic disorders or those undergoing treatment for conditions affecting protein metabolism.
How is the test performed?
A small needle is used to draw blood from a vein in your arm. The blood sample is sent to a lab where it’s analyzed to measure isoleucine concentration. The process usually takes a few minutes, and you may feel slight discomfort but no lasting effects.
Do I need to prepare for this test?
No special preparation is typically required. However, inform your doctor if you’re on a special diet, taking medications that affect metabolism, or have recent illness. Avoiding alcohol or strenuous activity for 24 hours before the test can sometimes improve accuracy.
  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