[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Biochemistry](https://durgical.com/en/biochemistry/) › Carnitine (L-carnitine)

[Biochemistry](https://durgical.com/en/biochemistry/) · Molecule

# Carnitine (L-carnitine)

Carnitine is the carrier that takes long-chain fatty acids into the mitochondrion to be burned.

Updated 2026-11-01

Loading the 3D model…

## Key facts

- Comes from meat and dairy and is made in liver and kidney from lysine and methionine (needs vitamin C).
- Enters cells through the OCTN2 transporter (SLC22A5 gene); the kidney reabsorbs it through the same transporter.
- Carries the acyl group as acylcarnitine across the inner membrane (CPT-I, CACT, CPT-II).
- Blood acylcarnitines are the basis of newborn screening for β-oxidation defects.

**Also called**
Levocarnitine, β-Hydroxy-γ-trimethylaminobutyrate

**Formula**
C₇H₁₅NO₃

**PubChem**
[CID 10917](https://pubchem.ncbi.nlm.nih.gov/compound/10917)

## Structure

- A small molecule with a quaternary ammonium and a hydroxyl group that forms the ester with the fatty acid.

## Clinical notes

- Primary deficiency (OCTN2): very low carnitine, hypoketotic hypoglycaemia and cardiomyopathy; responds to oral carnitine.
- Secondary deficiency: dialysis, valproic acid, organic acidurias (lost as acylcarnitine) and some formulas.

## Pathways

- [Fatty acid β-oxidation](https://durgical.com/en/biochemistry/pathways/fatty-acid-oxidation/)

## Related conditions

- [Primary carnitine deficiency](https://durgical.com/en/conditions/primary-carnitine-deficiency/)
- [Carnitine palmitoyltransferase II (CPT-II) deficiency](https://durgical.com/en/conditions/carnitine-palmitoyltransferase-ii-deficiency/)
- [Medium-chain acyl-CoA dehydrogenase (MCAD) deficiency](https://durgical.com/en/conditions/medium-chain-acyl-coa-dehydrogenase-deficiency/)

## Related

- [Carnitine shuttle](https://durgical.com/en/biochemistry/topics/carnitine-shuttle/)
- [Carnitine palmitoyltransferase I (CPT-I)](https://durgical.com/en/biochemistry/enzymes/carnitine-palmitoyltransferase-i/)
- [Palmitate (palmitic acid)](https://durgical.com/en/biochemistry/molecules/palmitate/)
- [Medium-chain acyl-CoA dehydrogenase (MCAD)](https://durgical.com/en/biochemistry/enzymes/medium-chain-acyl-coa-dehydrogenase/)

## Test yourself

Think of the answer, then tap the question to see it.

## Which transporter carries carnitine into cells?

OCTN2, encoded by SLC22A5; it also reabsorbs carnitine in the kidney.

## From which amino acids is carnitine made?

From lysine and methionine, with the help of vitamin C.

## Why can valproic acid lower carnitine?

It forms valproylcarnitine, which is lost in urine and drags free carnitine with it.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/biochemistry/molecules/carnitine/)

Molecules are shown in their neutral form, as the databases deposit them; in the cell the acids and phosphates are ionised.

Educational information, not medical advice. For any symptom, see a health professional.

Sources: [(-)-Carnitine (CID 10917)](https://pubchem.ncbi.nlm.nih.gov/compound/10917) (PubChem, NCBI, 2026) · Public domain; [Carnitine shuttle](https://reactome.org/PathwayBrowser/#/R-HSA-200425) (Reactome, 2026); [SLC22A5 gene: MedlinePlus Genetics](https://medlineplus.gov/genetics/gene/slc22a5/) (MedlinePlus, US National Library of Medicine, 2026).

[← All of biochemistry](https://durgical.com/en/biochemistry/)

## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake

Representative model, for educational purposes only.

---
Source: https://durgical.com/en/biochemistry/molecules/carnitine/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/biochemistry/molecules/carnitine/