Carnitine deficiency

[Vania]

Carnitine deficiency results from inadequate intake of or inability to metabolize the amino acid carnitine. It can cause a heterogeneous group of disorders. Muscle metabolism is impaired, causing myopathy, hypoglycemia, or cardiomyopathy. Infants typically present with hypoglycemic, hypoketotic encephalopathy. Most often, treatment consists of dietary L-carnitine.
(See also Overview of Undernutrition.)
The amino acid carnitine is required for the transport of long-chain fatty acyl coenzyme A (CoA) esters into myocyte mitochondria, where they are oxidized for energy. Carnitine is obtained from foods, particularly animal-based foods, and via endogenous synthesis.
Causes of carnitine deficiency include the following:

Inadequate intake (eg, due to fad diets, lack of access, or long-term total parenteral nutrition)
Inability to metabolize carnitine due to enzyme deficiencies (eg, carnitine palmitoyltransferase deficiency, methylmalonicaciduria, propionicacidemia, isovalericacidemia)
Decreased endogenous synthesis of carnitine due to a severe liver disorder
Excess loss of carnitine due to diarrhea, diuresis, or hemodialysis
A hereditary disorder in which carnitine leaks from renal tubules
Increased requirements for carnitine when ketosis is present or demand for fat oxidation is high (eg, during a critical illness such as sepsis or major burns; after major surgery of the gastrointestinal tract)
Decreased muscle carnitine levels due to mitochondrial impairment (eg, due to use of zidovudine )
Use of valproate

The deficiency may be generalized (systemic) or may affect mainly muscle (myopathic).