Role of L‑Carnitine in Energy Metabolism and Clinical Practice

Mechanism of Fatty‑Acid Transport

Contribution to Glucose Metabolism

Endogenous Synthesis and Dietary Supply

Role in Critical Illness and Sepsis

Anti‑Inflammatory Effects in Renal Failure

Indications for Supplementation

• Pediatric patients expected to receive parenteral nutrition for >4 weeks,
• Premature infants on an individual basis, and
• Patients with renal or hepatic insufficiency who are at risk of deficiency due to impaired endogenous synthesis.

Pharmacokinetics and Bioavailability

Clinical Use and Dosing of L‑Carnitine

Terminology and Biological Activity

• In clinical practice, “carnitine” and “L‑carnitine” are used interchangeably because L‑carnitine is the sole biologically active and therapeutically useful stereoisomer. 7

Endogenous Synthesis

• L‑carnitine is endogenously synthesized in the kidney and liver from the amino acids lysine and methionine, and healthy individuals—including strict vegetarians—produce adequate amounts without the need for supplementation. 7

Supplementation Dosing

• Preventive supplementation in patients at risk of deficiency (e.g., those receiving prolonged parenteral nutrition or continuous renal replacement therapy) is typically 0.5–1 g per day. Therapeutic dosing for confirmed deficiency is usually 50–100 mg/kg per day, often amounting to about 3 g per day in adults. [8][9]

Dietary Sources

• The richest dietary source of L‑carnitine is red meat, with concentrations increasing proportionally to the redness of the meat; fish, poultry, and milk also provide measurable amounts. 7