Carnitine (Free and Total) in Serum or Plasma
This test measures the amount of carnitine, a substance that helps move fatty acids into cells to be used for energy. Carnitine plays a key role in metabolism and can be important for heart, muscle, and nerve function.
["Carnitine helps convert fats into energy and supports cellular function; low levels may signal metabolic or muscle disorders."]
Key facts at a glance
- LOINC
- 10561-9
- Short code
- CARN-SEM
- Synonyms
- Carnitine Smn-sCnc
- Category
- chemistry
- Sample
- serum
- Container
- Sterile, wide-mouthed, leak-proof specimen container; specimen must be collected in a clinical setting or per laboratory-specific instructions
- Units
- N/A
- Ref low
- 10
- Ref high
- 50
- Fasting
- false
- Population
- adult
- Sex
- male
- Age range
- 18–99 years
- Method
- Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) or Enzymatic Colorimetric Assay
- CPT
- 82542 (Carnitine, quantitative)
- SNOMED
- 43072000 | 1007131000124101
- Specimen volume
- 1-2 mL of ejaculate; entire ejaculate preferred for accurate assessment
- Stability
- Specimen should be analyzed within 1-2 hours of collection. If delayed, seminal plasma should be separated by centrifugation and stored at -20°C or -80°C for long-term stability (up to 3 months).
- Hemolysis max
- 500
- Lipemia max
- 1000
- Icterus max
- 500
- TAT
- 48–168 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may order this test if you have symptoms like muscle weakness, fatigue, heart problems, or unexplained weight changes. It could also be part of a broader evaluation for metabolic disorders, genetic conditions, or conditions affecting how your body uses fats for energy. Sometimes, it’s checked in people with kidney disease, liver disease, or those on certain medications that affect carnitine levels.
What to Expect Before the Test
No special preparation is usually needed, but your provider may ask you to fast for a few hours before the test if it involves drawing blood. If you’re taking medications that could affect carnitine levels (like certain antibiotics or diuretics), let your provider know. If you’re pregnant or breastfeeding, discuss it with your provider before the test.
What the Test Results Mean
Results can vary based on your health, diet, and other factors. Your provider will compare your results to what’s typical for healthy adults and consider your medical history and symptoms. Very low levels might suggest conditions like primary carnitine deficiency, mitochondrial disorders, or kidney problems, while very high levels could indicate muscle breakdown or certain metabolic syndromes.
Common Conditions Linked to Carnitine Levels
Abnormal carnitine levels can be linked to conditions like carnitine palmitoyltransferase (CPT) deficiencies, mitochondrial disorders, or disorders affecting how your body uses fats. Low levels may also be seen in people with kidney disease, liver disease, or those who have undergone certain surgeries (like bariatric surgery). High levels can sometimes be a sign of muscle damage or certain metabolic imbalances.
Reference range
Reference ranges for carnitine in semen are not well-established; clinical interpretation should be based on laboratory-specific reference values and clinical context. Generally, total carnitine in seminal plasma has been reported in the range of 10-50 µmol/L in fertile males.N/A
Patient should abstain from ejaculation for 2-5 days prior to specimen collection. No fasting required. Patient should be informed about proper collection technique to avoid contamination.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Carnitine levels are important because they reflect how well your body is converting fats into energy. Low levels can interfere with energy production in cells, especially in heart, muscle, and nerve tissues. Your provider will use the test results along with your symptoms and medical history to guide treatment decisions, which might include dietary changes, supplements, or medications.
Short name
Carnitine Levels
Frequently asked questions
What causes carnitine levels to be low?
What are the typical symptoms of abnormal carnitine levels?
Can carnitine levels be affected by diet?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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