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Acylcarnitinepatternspecimp

Published: August 9, 2026Updated: August 10, 2026

A blood test that measures different types of acylcarnitines to help detect inherited metabolic disorders affecting how the body processes fats for energy.

Quick summary

{"Measures specific molecules (acylcarnitines) in your blood","Helps diagnose fatty acid oxidation disorders and organic acidemias","Commonly used for newborn screening follow-up or when symptoms suggest a metabolic problem","Requires a small blood sample drawn from a vein","Results help doctors identify rare but treatable genetic metabolic conditions"}

Medically reviewed by WellAlly Editorial TeamLast reviewed August 10, 2026Editorial policy

Key facts at a glance

LOINC
50164-3
Short code
ACYLP
Synonyms
Acylcarnitine pattern Spec-Imp
Category
chemistry
Sample
serum
Container
Serum separator tube (SST) or dried blood spot (DBS) card
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
≥ 0 years
Method
Tandem Mass Spectrometry (MS/MS)
CPT
82017
SNOMED
122465009
Specimen volume
0.5 mL serum minimum; 3-4 blood spots for DBS
Stability
Serum: 7 days at 2-8°C, 30 days at -20°C. DBS: 7 days at room temperature, 30 days refrigerated. Avoid repeated freeze-thaw cycles.
Hemolysis max
50
Lipemia max
100
Icterus max
20
TAT
48–96 hours
Order
routine

What is this test?

The acylcarnitine pattern test is a specialized blood test that measures the levels of different acylcarnitine molecules in your blood. Acylcarnitines are substances produced when your body breaks down fatty acids for energy. This test helps doctors see if there is an abnormal pattern that might indicate an inherited metabolic disorder.

Why is it ordered?

This test is typically ordered for one of two reasons: (1) as a follow-up to abnormal newborn screening results, or (2) when a person - especially a child - shows symptoms of a metabolic disorder such as recurrent vomiting, low blood sugar, muscle weakness, developmental delays, or unexplained metabolic crises. It helps identify conditions where the body cannot properly convert fats into energy.

How is the test performed?

A healthcare professional will draw a small sample of blood from a vein in your arm. The blood is collected into a special tube and sent to a laboratory for analysis. The test measures various acylcarnitine species, which can indicate specific types of metabolic disorders. No special preparation (like fasting) is usually required, but follow your doctor's instructions.

What do the results mean?

The results show the levels of different acylcarnitines. An abnormal pattern - where certain acylcarnitines are too high or too low - can suggest specific metabolic disorders. Your doctor will interpret the results based on your symptoms, medical history, and other tests. If an abnormality is found, genetic counseling and additional testing may be recommended.

Reference range

Normal acylcarnitine pattern. No abnormal elevations detected. Specific acylcarnitine species are evaluated against age-appropriate reference ranges. Interpretation considers the overall pattern rather than individual values.N/A

Specimen: serum

No special preparation required. Test can be performed on both fasting and non-fasting patients. For newborn screening, specimen should be collected prior to any metabolic treatment interventions.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Frequently asked questions

Is fasting required before the test?
Fasting is not always required for this test. However, some doctors may ask that the blood sample be taken after a period of fasting to help reveal certain disorders. Always follow the specific instructions given by your healthcare provider.
Does the test hurt?
You may feel a brief pinch or sting when the needle is inserted to draw blood. The discomfort is usually minimal and short-lived. The amount of blood taken is small - typically just a few milliliters.
How long does it take to get results?
Results are usually available within a few days to a week, depending on the laboratory. Your doctor will contact you with the results or discuss them at a follow-up appointment.
What happens if my results are abnormal?
An abnormal result does not always mean you have a serious condition. Your doctor will likely order additional tests to confirm a diagnosis. If a metabolic disorder is confirmed, treatment may include dietary changes, supplements, and careful management to prevent metabolic crises.
Is this test only for children?
No. While it is commonly used in newborn screening, this test can be ordered for people of any age when symptoms suggest a possible metabolic disorder. Adults may be tested if they have unexplained symptoms like muscle pain, exercise intolerance, or metabolic problems.
  1. 1
    Mayo Clinic Laboratories - Acylcarnitine Profile, Quantitative, SerumSource
  2. 2
    American College of Medical Genetics and Genomics - Newborn Screening ACT SheetsSource

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 10, 2026. · Read our editorial policy