Understanding Your Laboratory Test: A Patient's Guide to What It Is and Why It Matters

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

This test measures the level of acetylcarnitine in the fluid surrounding the brain and spinal cord to help diagnose metabolic and neurological disorders.

Quick summary

{"Measures acetylcarnitine levels in cerebrospinal fluid (CSF)","Helps diagnose metabolic and neurological conditions","Abnormal results may indicate mitochondrial disorders or fatty acid oxidation problems","Sample is collected via lumbar puncture (spinal tap)","Results help doctors understand how your body produces energy for brain cells"}

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

Key facts at a glance

LOINC: 50155-1
Short code: C2 CSF
Synonyms: Acetylcarn CSF-sCnc
Category: chemistry
Sample: csf
Container: Sterile polypropylene cryovial
Units: N/A
Ref low: 1.5
Ref high: 8
Fasting: false
Population: adult
Sex: all
Age range: 0–100 years
Method: Liquid chromatography-tandem mass spectrometry (LC-MS/MS)
CPT: 82542
SNOMED: 373403006
Specimen volume: 0.5-1.0 mL of cerebrospinal fluid
Stability: Stable for 24 hours at 2-8°C; freeze at -20°C for longer storage (up to 2 weeks); avoid repeated freeze-thaw cycles
Hemolysis max: 200
TAT: 72–168 hours
Order: routine

What is this test and what does it measure in my body?

The acetylcarnitine (C2) test measures the amount of acetylcarnitine in your cerebrospinal fluid (CSF). CSF is the clear fluid that surrounds and protects your brain and spinal cord. Acetylcarnitine is a specialized form of carnitine that plays a crucial role in energy production within brain cells. It helps transport fatty acids into the mitochondria, where they are converted into energy that brain cells need to function properly.

Why might my doctor order this test and what can the results show?

This test is typically ordered when doctors suspect a metabolic or neurological disorder affecting brain energy metabolism. It helps evaluate conditions related to mitochondrial function, fatty acid oxidation, and overall brain health. The test may be part of a broader investigation into unexplained neurological symptoms.

How is the sample for this test collected and what can I expect during the process?

The CSF sample is collected through a procedure called a lumbar puncture, commonly known as a spinal tap. During this procedure, a healthcare provider inserts a thin needle into the lower back to withdraw a small amount of cerebrospinal fluid. The area is numbed first to minimize discomfort. The procedure typically takes about 15-30 minutes.

How should I prepare for this test before my appointment?

Your doctor will provide specific instructions. Generally, you should inform your doctor about all medications you are taking, as some drugs may affect test results. You may be asked to stop certain medications temporarily. It's important to follow your doctor's instructions regarding fasting or other preparations.

Reference range

Reference range: 1.5-8.0 micromoles per liter (umol/L). Values may vary by laboratory methodology and reference population.N/A

Specimen: csf

No special preparation required. Patient should remain in lateral decubitus position during lumbar puncture procedure.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Abnormal acetylcarnitine levels in CSF can indicate several health conditions. Elevated levels may suggest mitochondrial disorders, where the energy-producing units in cells don't function properly. It may also indicate fatty acid oxidation disorders, which affect how the body breaks down fats for energy. Low levels might point to carnitine deficiency or problems with energy metabolism in the brain. This test helps doctors distinguish between different types of metabolic and neurological disorders, guide treatment decisions, and monitor disease progression or response to therapy.

Frequently asked questions

Is the lumbar puncture procedure painful?

The area is numbed with local anesthesia, so you may feel some pressure but minimal pain during the procedure. Some people experience a brief headache afterward, which can usually be managed with rest and fluids.

How long does it take to get results?

Results typically take several days to a week, as the analysis requires specialized laboratory testing. Your doctor will contact you with the results and explain what they mean for your health.

What do abnormal results mean?

Abnormal results don't always mean you have a serious condition. Your doctor will interpret the results in context with your other test results, symptoms, and medical history to determine the appropriate next steps.

Will I need to fast before this test?

Your doctor will provide specific instructions. In some cases, fasting may be required, while in others it may not be necessary. Follow your healthcare provider's instructions carefully.

Sources

1
MedlinePlus - CarnitineSource
2
Mayo Clinic Laboratories - AcetylcarnitineSource

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