Platform
Company
Metabolic Disorders
Review status
Currently under review
Pending specialist review and validation.
This test measures the total amount of carnitine in your blood, which includes both free carnitine and acylcarnitines. Carnitine is a carrier molecule that helps move fatty acids into mitochondria so your cells can make energy, especially in the heart and muscles. The measurement is usually performed by tandem mass spectrometry as part of an acylcarnitine profile.
Total carnitine helps your care team assess how well your body transports and uses fats for energy. It is commonly ordered along with free carnitine and a detailed acylcarnitine pattern to evaluate for nutritional issues, inherited metabolic conditions, and to monitor response to treatment.
Your body needs adequate carnitine to fuel the heart, skeletal muscles, and other organs. Low levels can be associated with primary carnitine transporter deficiency, secondary disturbances from fatty acid oxidation disorders, liver or kidney disease, malnutrition, or the effects of certain medicines. High levels can occur with supplementation or reduced kidney clearance. This test can be helpful when there are symptoms like poor exercise tolerance, muscle weakness, low energy, enlarged heart, or when a newborn screen or previous labs suggest a carnitine problem.
Clinicians also use total carnitine to guide and monitor carnitine supplementation, to distinguish primary deficiency from secondary causes, and to assess recovery during treatment. Timely identification and management can reduce the risk of complications affecting the heart, muscles, and blood sugar control.
Results are interpreted together with free carnitine, the acylcarnitine profile, and your clinical picture. A low total carnitine can point to reduced intake, impaired transport, increased loss, or increased utilization during illness. In infants, a low result may reflect the mother’s carnitine status, so both the child and the birthing parent may need evaluation. A high result may reflect recent supplementation or decreased kidney excretion. Because patterns matter, ratios and specific acylcarnitine findings often help clarify the cause.
If your result is outside the expected range, your clinician may repeat testing, review medicines and diet, and consider additional studies such as urine carnitine, kidney and liver tests, or genetic testing when a hereditary condition is suspected. Do not start, stop, or change carnitine or other supplements without medical guidance, since targeted therapy and follow‑up should be individualized.
Reference intervals vary by laboratory, analyzer, methodology, population, and units. The ranges shown here are for education only. Always interpret your results against the reference interval printed on your own lab report.
Acute illness, recent strenuous exercise, or prolonged fasting can shift fatty acid use and alter acylcarnitine patterns, which may influence total carnitine interpretation. Tell your clinician about recent symptoms or exertion.
Results can vary slightly between serum, plasma, and dried blood spot testing. Delayed processing or improper storage may affect analyte stability. Consistent collection and prompt processing help ensure reliable results.
L‑carnitine supplements, certain energy products, high‑meat intake, or specialized diets such as ketogenic regimens can change measured levels. Provide a full list of supplements and recent diet to your care team.
Some medicines, including valproate and pivalate‑containing antibiotics, can lower carnitine. Others may influence kidney handling. Share all prescriptions, over‑the‑counter drugs, and recent antibiotics with your clinician.
Kidney disease can reduce carnitine clearance, raising levels, while dialysis can remove carnitine and lower them. Liver disease and severe malnutrition can reduce synthesis or stores, affecting test results.
Pregnancy and the newborn period can influence carnitine status. A low result in a newborn may be secondary to maternal deficiency, so paired evaluation is sometimes recommended.
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