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Fatty Acid Profile (Long-Chain Fatty Acids) in Serum

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

This test measures the levels of long-chain fatty acids in your blood serum, which can help assess metabolic health, particularly in conditions involving fat metabolism or storage.

Quick summary

["Long-chain fatty acids are crucial for energy production and cell membrane function; abnormal levels may signal metabolic disorders."]

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

Key facts at a glance

LOINC
32545-6
Short code
Fat 72h Stl-sRate
Synonyms
Fat 72h Stl-sRate
Category
chemistry
Sample
stool
Container
Clean container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
5 g
Stability
Refrigerated: 24h, Frozen: 7d
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 fatigue, muscle weakness, or signs of metabolic disorders. It could also be part of a broader evaluation for conditions like fatty liver disease, mitochondrial disorders, or certain genetic metabolic syndromes.

What to Expect Before the Test

No special preparation is typically needed, but you may be asked to fast for 8–12 hours before the blood draw if your provider directs it. Bring any medications you’re currently taking to your appointment.

What the Results Mean

Results show the concentration of specific long-chain fatty acids in your blood. While reference ranges vary by lab, elevated levels may indicate inefficient fat metabolism, while lower levels could suggest deficiencies or other metabolic issues.

Common Conditions Monitored

This test is often used to monitor conditions like carnitine deficiency, mitochondrial disorders, or metabolic syndromes where fat metabolism is disrupted. It may also help diagnose or track treatment progress in rare genetic disorders.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Long-Chain Fatty Acid Analysis

Frequently asked questions

What does it cost?
The cost of this test varies by lab, insurance coverage, and location. Check with your healthcare provider or insurance company for an estimate. Some labs may offer bundled metabolic panels that include this test at a reduced cost.
How often should I get this test?
Frequency depends on your health status. If you have a known metabolic disorder, your provider may recommend regular monitoring. Otherwise, this test is usually ordered as needed for specific symptoms or investigations.
Can I eat or drink before this test?
Follow your provider’s instructions, but generally, fasting for 8–12 hours is recommended if directed. Avoid caffeine or heavy meals before the blood draw to ensure accurate 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