Record Information
Creation Date2005-11-16 15:48:42 UTC
Update Date2013-04-14 22:29:59 UTC
Secondary Accession Numbers
  • HMDB01467
Metabolite Identification
Common NameL-Carnitine
DescriptionCarnitine is not an essential amino acid; it can be synthesized in the body. However, it is so important in providing energy to muscles including the heart-that some researchers are now recommending carnitine supplements in the diet, particularly for people who do not consume much red meat, the main food source for carnitine. Carnitine has been described as a vitamin, an amino acid, or a metabimin, i.e., an essential metabolite. Like the B vitamins, carnitine contains nitrogen and is very soluble in water, and to some researchers carnitine is a vitamin (Liebovitz 1984). It was found that an animal (yellow mealworm) could not grow without carnitine in its diet. However, as it turned out, almost all other animals, including humans, do make their own carnitine; thus, it is no longer considered a vitamin. Nevertheless, in certain circumstances-such as deficiencies of methionine, lysine or vitamin C or kidney dialysis--carnitine shortages develop. Under these conditions, carnitine must be absorbed from food, and for this reason it is sometimes referred to as a "metabimin" or a conditionally essential metabolite. Like the other amino acids used or manufactured by the body, carnitine is an amine. But like choline, which is sometimes considered to be a B vitamin, carnitine is also an alcohol (specifically, a trimethylated carboxy-alcohol). Thus, carnitine is an unusual amino acid and has different functions than most other amino acids, which are most usually employed by the body in the construction of protein. Carnitine is an essential factor in fatty acid metabolism in mammals. It's most important known metabolic function is to transport fat into the mitochondria of muscle cells, including those in the heart, for oxidation. This is how the heart gets most of its energy. In humans, about 25% of carnitine is synthesized in the liver, kidney and brain from the amino acids lysine and methionine. Most of the carnitine in the body comes from dietary sources such as red meat and dairy products. Inborn errors of carnitine metabolism can lead to brain deterioration like that of Reye's syndrome, gradually worsening muscle weakness, Duchenne-like muscular dystrophy and extreme muscle weakness with fat accumulation in muscles. Borurn et al. (1979) describe carnitine as an essential nutrient for pre-term babies, certain types (non-ketotic) of hypoglycemics, kidney dialysis patients, cirrhosis, and in kwashiorkor, type IV hyperlipidemia, heart muscle disease (cardiomyopathy), and propionic or organic aciduria (acid urine resulting from genetic or other anomalies). In all these conditions and the inborn errors of carnitine metabolism, carnitine is essential to life and carnitine supplements are valuable. carnitine therapy may also be useful in a wide variety of clinical conditions. carnitine supplementation has improved some patients who have angina secondary to coronary artery disease. It may be worth a trial in any form of hyperlipidemia or muscle weakness. carnitine supplements may be useful in many forms of toxic or metabolic liver disease and in cases of heart muscle disease. Hearts undergoing severe arrhythmia quickly deplete their stores of carnitine. Athletes, particularly in Europe, have used carnitine supplements for improved endurance. carnitine may improve muscle building by improving fat utilization and may even be useful in treating obesity. carnitine joins a long list of nutrients which may be of value in treating pregnant women, hypothyroid individuals, and male infertility due to low motility of sperm. Even the Physician's Desk Reference gives indication for carnitine supplements as "improving the tolerance of ischemic heart disease, myocardial insufficiencies, and type IV hyperlipoproteinemia. carnitine deficiency is noted in abnormal liver function, renal dialysis patients, and severe to moderate muscular weakness with associated anorexia." (
  1. (-)-(R)-3-Hydroxy-4-(trimethylammonio)butyrate
  2. (-)-carnitine
  3. (R)-(3-Carboxy-2-hydroxypropyl)trimethylammonium hydroxide
  4. (R)-carnitine
  5. (S)-carnitine
  6. 1-Carnitine
  7. 3-Carboxy-2-hydroxy-N,N,N-trimethyl-1-propanaminium
  8. 3-Hydroxy-4-trimethylammoniobutanoate
  9. 3-Hydroxy-4-trimethylammoniobutanoic acid
  10. Bicarnesine
  11. Carniking
  12. Carniking 50
  13. Carnilean
  14. Carnipass
  15. Carnipass 20
  16. Carnitene
  17. Carnitine
  18. Carnitor
  19. D-Carnitine
  20. delta-Carnitine
  21. DL-carnitine
  22. gamma-Trimethyl-ammonium-beta-hydroxybutirate
  23. gamma-Trimethyl-beta-hydroxybutyrobetaine
  24. gamma-Trimethyl-hydroxybutyrobetaine
  25. Karnitin
  26. L-(-)-Carnitine
  27. L-Carnitine
  28. L-gamma-Trimethyl-beta-hydroxybutyrobetaine
  29. Levocarnitina
  30. Levocarnitine
  31. Levocarnitinum
  32. R-(-)-3-Hydroxy-4-trimethylaminobutyrate
  33. Vitamin BT
Chemical FormulaC7H15NO3
Average Molecular Weight161.1989
Monoisotopic Molecular Weight161.105193351
IUPAC Name(3R)-3-hydroxy-4-(trimethylazaniumyl)butanoate
Traditional IUPAC NameL-carnitine
CAS Registry Number541-15-1
InChI Identifier
Chemical Taxonomy
KingdomOrganic Compounds
Super ClassAliphatic Acyclic Compounds
Sub ClassQuaternary Ammonium Salts
Other Descriptors
  • Aliphatic Acyclic Compounds
  • a D,L-carnitine(Cyc)
  • amino-acid betaine(ChEBI)
  • gamma-amino acid(ChEBI)
  • Beta Hydroxy Acid
  • Carboxylic Acid Salt
  • Choline
  • Secondary Alcohol
Direct ParentCarnitines
StatusDetected and Quantified
  • Endogenous
  • Component of Alanine and aspartate metabolism
  • Component of Fatty acid metabolism
  • Essential amino acid
ApplicationNot Available
Cellular locations
  • Cytoplasm
  • Extracellular
  • Mitochondria
  • Endoplasmic reticulum
  • Peroxisome
Physical Properties
Experimental Properties
Melting Point197 °CNot Available
Boiling PointNot AvailableNot Available
Water SolubilityNot AvailableNot Available
LogPNot AvailableNot Available
Predicted Properties
water solubility5.33 g/LALOGPS
pKa (strongest acidic)4.2ChemAxon
pKa (strongest basic)-3.6ChemAxon
physiological charge0ChemAxon
hydrogen acceptor count3ChemAxon
hydrogen donor count1ChemAxon
polar surface area60.36ChemAxon
rotatable bond count4ChemAxon
SpectraNot Available
Biological Properties
Cellular Locations
  • Cytoplasm
  • Extracellular
  • Mitochondria
  • Endoplasmic reticulum
  • Peroxisome
Biofluid Locations
  • Blood
  • Cerebrospinal Fluid (CSF)
  • Urine
Tissue Location
  • Adipose Tissue
  • Bladder
  • Brain
  • Erythrocyte
  • Fibroblasts
  • Intestine
  • Kidney
  • Liver
  • Lung
  • Muscle
  • Myocardium
  • Nerve Cells
  • Neuron
  • Platelet
  • Prostate
  • Skeletal Muscle
  • Sperm
  • Testes
Beta Oxidation of Very Long Chain Fatty AcidsSMP00052map01040
Carnitine SynthesisSMP00465Not Available
Mitochondrial Beta-Oxidation of Long Chain Saturated Fatty AcidsSMP00482Not Available
Mitochondrial Beta-Oxidation of Short Chain Saturated Fatty AcidsSMP00480Not Available
Oxidation of Branched Chain Fatty AcidsSMP00030Not Available
Normal Concentrations
BloodDetected and Quantified29.74 +/- 7.55 uMAdult (>18 years old)Not SpecifiedNormal
BloodDetected and Quantified33.6 +/- 6.2 uMChildren (1-13 year old)BothNormal
  • Geigy Scient...
BloodDetected and Quantified38.2 +/- 5.4 uMAdult (>18 years old)FemaleNormal
  • Geigy Scient...
BloodDetected and Quantified43.0 (26.0-79.0) uMAdult (>18 years old)BothNormal
BloodDetected and Quantified45.7 +/- 11.6 uMAdult (>18 years old)Not SpecifiedNormal
Cerebrospinal Fluid (CSF)Detected and Quantified1.900 +/- 0.474 uMAdult (>18 years old)BothNormal
Cerebrospinal Fluid (CSF)Detected and Quantified4.0 (2.0 - 9.0) uMAdult (>18 years old)BothNormal
UrineDetected but not QuantifiedNot ApplicableAdult (>18 years old)MaleNormal
UrineDetected but not QuantifiedNot ApplicableAdult (>18 years old)BothNormal
UrineDetected and Quantified4.5 (0.62-15.2) umol/mmol creatinineAdult (>18 years old)BothCommentNormal
UrineDetected and Quantified5.0 (0.7-16.4) umol/mmol creatinineAdult (>18 years old)BothCommentNormal
UrineDetected and Quantified3.17 umol/mmol creatinineAdult (>18 years old)MaleNormal
  • Shaykhutdino...
UrineDetected and Quantified5.7 +/- 4.8 umol/mmol creatinineAdult (>18 years old)FemaleNormal
  • Geigy Scient...
UrineDetected and Quantified23.5 +/- 4.0 umol/mmol creatinineAdult (>18 years old)MaleNormal
  • Geigy Scient...
  • West Cadwell...
  • Basel, Switz...
UrineDetected and Quantified18.0 +/- 1.2 umol/mmol creatinineAdult (>18 years old)FemaleNormal
  • Geigy Scient...
  • West Cadwell...
  • Basel, Switz...
Abnormal Concentrations
BloodDetected and Quantified41.7 +/- 23.9 uMAdult (>18 years old)Not SpecifiedHeart Transplant
UrineDetected and Quantified13.3 (11.6-15.1) umol/mmol creatinineAdult (>18 years old)BothCommentDiabetes
UrineDetected and Quantified41.3 (38.3-44.2) umol/mmol creatinineAdult (>18 years old)BothCommentDiabetes
UrineDetected and Quantified7.0 (0.0-30.0) umol/mmol creatinineNot SpecifiedBothLung cancer
Associated Disorders and Diseases
Disease References
Diabetes mellitus type 2
  • Hoppel CL, Genuth SM: Urinary excretion of acetylcarnitine during human diabetic and fasting ketosis. Am J Physiol. 1982 Aug;243(2):E168-72. Pubmed: 6810706
Lung Cancer
  • Wishart DS, Knox C, Guo AC, Eisner R, Young N, Gautam B, Hau DD, Psychogios N, Dong E, Bouatra S, Mandal R, Sinelnikov I, Xia J, Jia L, Cruz JA, Lim E, Sobsey CA, Shrivastava S, Huang P, Liu P, Fang L, Peng J, Fradette R, Cheng D, Tzur D, Clements M, Lewis A, De Souza A, Zuniga A, Dawe M, Xiong Y, Clive D, Greiner R, Nazyrova A, Shaykhutdinov R, Li L, Vogel HJ, Forsythe I: HMDB: a knowledgebase for the human metabolome. Nucleic Acids Res. 2008 Oct 25. Pubmed: 18953024
Associated OMIM IDs
DrugBank IDDB00583
DrugBank Metabolite IDNot Available
Phenol Explorer Compound IDNot Available
Phenol Explorer Metabolite IDNot Available
FoodDB IDFDB000572
KNApSAcK IDNot Available
Chemspider ID2006614
KEGG Compound IDC15025
BiGG ID34600
Wikipedia LinkL-Carnitine
NuGOwiki LinkHMDB00062
Metagene LinkHMDB00062
PubChem Compound2724480
ChEBI ID11060
Synthesis Reference Bols, Mikael; Lundt, Inge; Pedersen, Christian. Simple synthesis of (R)-carnitine from D-galactono-1,4-lactone. Tetrahedron (1992), 48(2), 319-24.
Material Safety Data Sheet (MSDS)Download (PDF)
General References
  1. Tamai I, China K, Sai Y, Kobayashi D, Nezu J, Kawahara E, Tsuji A: Na(+)-coupled transport of L-carnitine via high-affinity carnitine transporter OCTN2 and its subcellular localization in kidney. Biochim Biophys Acta. 2001 Jun 6;1512(2):273-84. Pubmed: 11406104
  2. Waldner R, Laschan C, Lohninger A, Gessner M, Tuchler H, Huemer M, Spiegel W, Karlic H: Effects of doxorubicin-containing chemotherapy and a combination with L-carnitine on oxidative metabolism in patients with non-Hodgkin lymphoma. J Cancer Res Clin Oncol. 2006 Feb;132(2):121-8. Epub 2005 Nov 8. Pubmed: 16283381
  3. Sreekumar A, Poisson LM, Rajendiran TM, Khan AP, Cao Q, Yu J, Laxman B, Mehra R, Lonigro RJ, Li Y, Nyati MK, Ahsan A, Kalyana-Sundaram S, Han B, Cao X, Byun J, Omenn GS, Ghosh D, Pennathur S, Alexander DC, Berger A, Shuster JR, Wei JT, Varambally S, Beecher C, Chinnaiyan AM: Metabolomic profiles delineate potential role for sarcosine in prostate cancer progression. Nature. 2009 Feb 12;457(7231):910-4. Pubmed: 19212411
  4. Wachter S, Vogt M, Kreis R, Boesch C, Bigler P, Hoppeler H, Krahenbuhl S: Long-term administration of L-carnitine to humans: effect on skeletal muscle carnitine content and physical performance. Clin Chim Acta. 2002 Apr;318(1-2):51-61. Pubmed: 11880112
  5. Evans AM, Fornasini G: Pharmacokinetics of L-carnitine. Clin Pharmacokinet. 2003;42(11):941-67. Pubmed: 12908852
  6. Pastoris O, Dossena M, Foppa P, Catapano M, Arbustini E, Bellini O, Dal Bello B, Minzioni G, Ceriana P, Barzaghi N: Effect of L-carnitine on myocardial metabolism: results of a balanced, placebo-controlled, double-blind study in patients undergoing open heart surgery. Pharmacol Res. 1998 Feb;37(2):115-22. Pubmed: 9572066
  7. Stephens FB, Constantin-Teodosiu D, Laithwaite D, Simpson EJ, Greenhaff PL: Insulin stimulates L-carnitine accumulation in human skeletal muscle. FASEB J. 2006 Feb;20(2):377-9. Epub 2005 Dec 20. Pubmed: 16368715
  8. Malaguarnera M, Pistone G, Astuto M, Dell'Arte S, Finocchiaro G, Lo Giudice E, Pennisi G: L-Carnitine in the treatment of mild or moderate hepatic encephalopathy. Dig Dis. 2003;21(3):271-5. Pubmed: 14571103
  9. Oey NA, van Vlies N, Wijburg FA, Wanders RJ, Attie-Bitach T, Vaz FM: L-carnitine is synthesized in the human fetal-placental unit: potential roles in placental and fetal metabolism. Placenta. 2006 Aug;27(8):841-6. Epub 2005 Nov 18. Pubmed: 16300828
  10. Feinfeld DA, Kurian P, Cheng JT, Dilimetin G, Arriola MR, Ward L, Manis T, Carvounis CP: Effect of oral L-carnitine on serum myoglobin in hemodialysis patients. Ren Fail. 1996 Jan;18(1):91-6. Pubmed: 8820505
  11. Matalliotakis I, Koumantaki Y, Evageliou A, Matalliotakis G, Goumenou A, Koumantakis E: L-carnitine levels in the seminal plasma of fertile and infertile men: correlation with sperm quality. Int J Fertil Womens Med. 2000 May-Jun;45(3):236-40. Pubmed: 10929687
  12. Vescovo G, Ravara B, Gobbo V, Dalla Libera L: Inflammation and perturbation of the l-carnitine system in heart failure. Eur J Heart Fail. 2005 Oct;7(6):997-1002. Pubmed: 16227137
  13. Lerch R: [The effect of L-carnitine on ischemic heart disease: experimental results] Schweiz Rundsch Med Prax. 1998 Jan 21;87(4):97-100. Pubmed: 9522638
  14. Khademi A, Alleyassin A, Safdarian L, Hamed EA, Rabiee E, Haghaninezhad H: The effects of L-carnitine on sperm parameters in smoker and non-smoker patients with idiopathic sperm abnormalities. J Assist Reprod Genet. 2005 Dec;22(11-12):395-9. Pubmed: 16331536
  15. Stradomska TJ, Tylki-Szymanska A, Bentkowski Z: Very long-chain fatty acids in Rett syndrome. Eur J Pediatr. 1999 Mar;158(3):226-9. Pubmed: 10094444
  16. Hoppel CL, Genuth SM: Urinary excretion of acetylcarnitine during human diabetic and fasting ketosis. Am J Physiol. 1982 Aug;243(2):E168-72. Pubmed: 6810706
  17. Lenzi A, Sgro P, Salacone P, Paoli D, Gilio B, Lombardo F, Santulli M, Agarwal A, Gandini L: A placebo-controlled double-blind randomized trial of the use of combined l-carnitine and l-acetyl-carnitine treatment in men with asthenozoospermia. Fertil Steril. 2004 Jun;81(6):1578-84. Pubmed: 15193480
  18. Sinclair C, Gilchrist JM, Hennessey JV, Kandula M: Muscle carnitine in hypo- and hyperthyroidism. Muscle Nerve. 2005 Sep;32(3):357-9. Pubmed: 15803480
  19. Ahmad S: L-carnitine in dialysis patients. Semin Dial. 2001 May-Jun;14(3):209-17. Pubmed: 11422928
  20. Shihabi ZK, Oles KS, McCormick CP, Penry JK: Serum and tissue carnitine assay based on dialysis. Clin Chem. 1992 Aug;38(8 Pt 1):1414-7. Pubmed: 1643708
  21. Steiber A, Kerner J, Hoppel CL: Carnitine: a nutritional, biosynthetic, and functional perspective. Mol Aspects Med. 2004 Oct-Dec;25(5-6):455-73. Pubmed: 15363636
  22. Olpin SE: Fatty acid oxidation defects as a cause of neuromyopathic disease in infants and adults. Clin Lab. 2005;51(5-6):289-306. Pubmed: 15991803


Gene Name:
Uniprot ID:
Acetyl-CoA + L-Carnitine unknown Coenzyme A + L-Acetylcarnitinedetails
Gene Name:
Uniprot ID:
Gene Name:
Uniprot ID:
Gene Name:
Uniprot ID:
Octanoyl-CoA + L-Carnitine unknown Coenzyme A + L-Octanoylcarnitinedetails
Gene Name:
Uniprot ID:
hexadecanoyl-CoA + L-Carnitine unknown Coenzyme A + L-Palmitoylcarnitinedetails
Gene Name:
Uniprot ID:
hexadecanoyl-CoA + L-Carnitine unknown Coenzyme A + L-Palmitoylcarnitinedetails
Gene Name:
Uniprot ID:
hexadecanoyl-CoA + L-Carnitine unknown Coenzyme A + L-Palmitoylcarnitinedetails
Gene Name:
Uniprot ID:
hexadecanoyl-CoA + L-Carnitine unknown Coenzyme A + L-Palmitoylcarnitinedetails
Gene Name:
Uniprot ID:
4-Trimethylammoniobutanoic acid + Oxoglutaric acid + Oxygen unknown L-Carnitine + Succinic acid + CO(2)details
4-Trimethylammoniobutanoic acid + Oxoglutaric acid + Oxygen unknown L-Carnitine + Succinic acid + Carbon dioxidedetails
Gene Name:
Uniprot ID:


Gene Name:
Uniprot ID:
Gene Name:
Uniprot ID:
Gene Name:
Uniprot ID: