Total Carnitine in Serum

Clinical Information

Carnitine, a water-soluble compound, is a collective for a number of compunds that include L-carnitine, acetyl-L-carnitine, and propionyl L-carnitine1,2. It can be ingested from food and endogenously synthesized2. It is conditionally essential3.

Carnitine is critical for energy production by transporting long-chain fatty acids (LCFA) into the mitochondria for oxidation. It also helps in the prevention of the accumulation of toxic compounds in the cell organelles1.

Signs and Symptoms of Deficiency or Toxicity

Deficiency is typically associated with reduced carnitine absorption or increased excretion, certain disorders such as chronic renal failure, or a genetic disorder1.

Primary carnitine deficiency typically manifests at 5 years of age with symptoms of cardiomyopathy, skeletal-muscle weakness, and hypoglycemia 1.

Adverse effects have been observed with intakes approximately 3 g/day. Too much carnitine can lead to nausea, vomiting, abdominal cramps, diarrhea, and a “fishy body odor”1.

Biomarker and Methods of Analysis


Serum total carnitine analysis is useful in the diagnosis and monitoring of patients with carnitine deficiency either primary or secondary which are the commonly diagnosed carnitine deficiency4.

Supplementation Guide

No established guidelines for prophylaxis for general nutrition3.

No upper limit established.

Treatment with anticonvulsants like valproic acid, phenobarbital, phenytoin, or carbamazepine can significantly reduce blood levels of carnitine1.

Food Sources

Meat, poultry, fish, and dairy products are excellent sources of L-carnitine whereas fruits, vegetables, and grains only have small amounts 5.

(1) Office of Dietary Supplements-National Institutes. (n.d.) Carnitine. Fact Sheet for Health Professionals. Retrieved from
(2) Adeva-Andany MM, Calvo-Castro I, Fernandez-Fernandez C, Donapetry-Garcia C, Pedre-Pineiro AM. Significance of l-carnitine for human health. IUMB 2017; 69(8):578-594. doi: 10.1002/iub.1646
(3) Flanagan JL, Simmons PA, Vehige J, Willcox MDP, Garrett Q. Role of carnitine in disease. Nutrition & Metabolism 2010; 7:30
(4) Mayo Clinic Medical Laboratories. (n.d.) Test Catalog. Carnitine, Plasma. Retrieved from
(5) Higdon J, Drake VJ. (April 2012). Linus Pauling Institute. Micronutrient Information Center. L-Carnitine. Retrieved from