Which clinical history findings are characteristic of secondary carnitine deficiency?

Updated: Dec 13, 2019
  • Author: Fernando Scaglia, MD, FACMG; Chief Editor: Maria Descartes, MD  more...
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Breastfed infants may experience a catabolic state shortly after birth, when the production of milk is not adequate to meet nutritional requirements. Acute metabolic decompensation with hypoketotic or nonketotic hypoglycemia usually occurs in infancy, whereas cardiac and skeletal muscle disease manifest later. The episodes of metabolic decompensation, triggered by fasting or common viral illness, consist of altered consciousness that can be complicated by seizures, apnea, or cardiorespiratory arrest. Patients may have a history of failure to thrive, developmental delay, or nonspecific abdominal problems.

Patients with organic acidemias causing secondary carnitine deficiency may present with crises consisting of hypoglycemia, ketoacidosis, and hyperammonemia.

Patients with respiratory chain defects or mitochondrial disorders and secondary carnitine deficiency may present with abnormal fatigability and lactic acidosis associated with exertion. These children also may present with encephalopathy and/or lipid storage myopathy and carnitine depletion. Carnitine deficiency has been observed in children with urea cycle defects, and it may exacerbate episodes of hyperammonemia.

Signs and symptoms related to carnitine deficiency are not completely defined in the newborn. Apnea, cardiac death, and sudden death have been found in infants with carnitine depletion.

Carnitine deficiency can develop in children with renal Fanconi tubulopathy; it may be idiopathic and present with renal tubular acidosis or secondary to acquired or inherited conditions.

Carnitine deficiency may present in children being treated with valproic acid and may be associated with fulminant liver failure and presentation similar to that in Reye syndrome. It also may present with a myopathy and increased lipid storage in patients with AIDS who are being treated with zidovudine.

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