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Acylcarnitineurscnc

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

This test measures the amount of acylcarnitine in your urine to help detect certain metabolic disorders that affect how your body processes fats for energy.

Quick summary

{"Measures acylcarnitine levels in urine to screen for metabolic disorders","Helps diagnose fatty acid oxidation disorders and organic acidemias","Commonly used in newborn screening programs","Abnormal results may indicate problems with energy metabolism","Early detection allows for better management and treatment"}

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

Key facts at a glance

LOINC
14283-6
Short code
ACYSTU
Synonyms
Acylcarnitine Ur-sCnc
Category
chemistry
Sample
urine
Container
Sterile, leak-proof urine container (preferred)
Units
N/A
Ref low
0
Ref high
1
Fasting
false
Population
adult
Sex
all
Age range
0–120 years
Method
Tandem Mass Spectrometry (MS/MS)
CPT
82017
SNOMED
313335003
Specimen volume
5-10 mL urine
Stability
Room temperature: 24 hours; Refrigerated (2-8°C): 7 days; Frozen (-20°C or below): 30 days
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
48–168 hours
Order
routine

What is this test?

The urine acylcarnitine test measures the levels of acylcarnitines in your urine. Acylcarnitines are substances produced when your body breaks down fatty acids for energy. Normally, your cells convert fatty acids into energy through a process called fatty acid oxidation. When this process doesn't work properly, acylcarnitines can build up in your body and spill into your urine.

Why do I need this test?

Your doctor may order this test to screen for or diagnose metabolic disorders, particularly fatty acid oxidation disorders and organic acidemias. These are genetic conditions where the body cannot properly convert fats into energy. The test is commonly part of newborn screening programs because early detection of these disorders can prevent serious complications.

How is the test done?

A urine sample is collected, typically in a sterile container. For newborns, a urine sample may be collected using a special collection bag. The sample is then sent to a laboratory where it is analyzed using techniques like tandem mass spectrometry to measure specific types of acylcarnitines.

What do the results mean?

Normal results vary by age and the specific type of acylcarnitine being measured. Abnormal results may indicate a metabolic disorder such as medium-chain acyl-CoA dehydrogenase deficiency (MCAD), carnitine palmitoyltransferase deficiency, or other organic acidemias. Your doctor will interpret the results based on your individual situation and may recommend additional testing.

Reference range

Reference ranges vary by specific acylcarnitine species. Generally, normal urine acylcarnitine excretion is <1 mmol/mol creatinine for most species. Interpretation requires comparison to age-specific reference intervals.N/A

Specimen: urine

No fasting required. Collect first morning urine specimen for optimal results. Avoid contamination with toilet paper or fecal material. Inform laboratory of any metabolic disorders or current medications.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings2

Frequently asked questions

Do I need to fast before this test?
For newborn screening, the test is typically done before any feeding changes. For older children or adults, your doctor may ask you to fast for a specific period before the test, as fasting can affect fatty acid metabolism and acylcarnitine levels. Always follow your doctor's specific instructions.
Is this test only done on newborns?
While it is commonly part of newborn screening programs, this test can be performed on individuals of any age when a metabolic disorder is suspected. Symptoms like unexplained fatigue, developmental delays, or episodes of illness triggered by fasting may prompt testing in older children or adults.
What happens if my results are abnormal?
If results are abnormal, your doctor will likely recommend additional testing to confirm the diagnosis. This may include blood tests, genetic testing, or repeat urine testing. A metabolic specialist will work with you to develop an appropriate treatment plan if a disorder is confirmed.
How long does it take to get results?
Results are typically available within a few days to a week, depending on the laboratory. For newborn screening programs, results are usually available within 1-2 weeks. Your healthcare provider will contact you if any follow-up is needed.
Are there any risks to this test?
The urine acylcarnitine test is very safe. The main risk is minimal and related to urine collection, such as slight discomfort or potential for a minor urinary tract infection. There are no known risks from the test itself.
  1. 1
    MedlinePlus - Newborn ScreeningSource
  2. 2
    Mayo Clinic - Metabolic DisordersSource
  3. 3
    American College of Medical Genetics - Acylcarnitine AnalysisSource

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