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Serum/plasma concentration of free fatty acids (medium-chain and long-chain)

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

This test measures the levels of free fatty acids in your blood, which are important energy sources for your body. They play a key role in metabolism and can be influenced by diet, exercise, and certain medical conditions.

Quick summary

["Free fatty acids help your body produce energy and maintain normal function, but their levels can be affected by health issues or lifestyle factors."]

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

Key facts at a glance

LOINC
6504-5
Short code
N men sg Y Ag CSF Ql IF
Synonyms
N men sg Y Ag CSF Ql IF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like unexplained weight changes, fatigue, or if you’re being evaluated for conditions such as diabetes, thyroid disorders, or metabolic syndrome. It may also be part of a broader evaluation for liver, kidney, or heart disease.

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 involves a blood draw. Avoid heavy meals or alcohol before testing. If you’re on certain medications, let your provider know.

What the Test Involves

A healthcare professional will draw blood from a vein in your arm. The sample is then sent to a lab for analysis. The process takes about 15 minutes, and you may feel slight discomfort but no lasting effects.

What the Results Mean

Results help assess your energy metabolism and identify potential imbalances. Elevated levels may suggest conditions like diabetes, starvation, or certain hormonal imbalances, while lower levels could indicate malnutrition or overuse of certain medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance

Short name

Free Fatty Acids (FFA) Profile

Frequently asked questions

What does my test result indicate?
Elevated free fatty acids might signal metabolic stress, such as uncontrolled diabetes or prolonged fasting. Lower levels could indicate inadequate fat intake or certain medications that suppress fat breakdown. Always discuss your results with your provider for personalized interpretation.
How often should I get this test?
This test is typically ordered as needed, often during routine check-ups or when symptoms or risk factors (like obesity or diabetes) are present. Your provider will determine the best timing based on your health status.
Can diet or exercise affect my results?
Yes, diet (especially high-fat meals) and exercise can influence free fatty acid levels. Fasting before the test helps provide more accurate results, but your provider will guide you on preparation.
  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