Definition:
Carnitine deficiency is a metabolic state in which carnitine concentrations in plasma and tissues are less than the levels needed for normal function of the organism. Biologic effects of low carnitine levels may not be clinically significant until they reach less than 10-20% of the norm.
Diagnosis:
Skin biopsy can be done to confirm diagnosis of primary carnitine deficiency by demonstrating reduced carnitine transport in fibroblasts that express the transporter. Fibroblasts may be utilized for fatty acid oxidation studies or enzyme assay.
Treatment:
In acute situations, if the patient presents with hypoketotic hypoglycemic encephalopathy, insure stabilization with 10% dextrose in water at rates of 10 mg/kg/min IV initially; adjust infusion rate depending on blood glucose concentrations.
Symptoms and Signs:
One classic initial presentation of primary carnitine deficiency is hypoketotic hypoglycemic encephalopathy, accompanied by hepatomegaly, hyperammonemia, and elevated liver transaminases. Cardiomyopathy is the other classic presentation (affecting older children); onset may arise with rapidly progressive heart failure. Cardiomyopathy can also be seen in older patients with a metabolic presentation, even if they are asymptomatic from a cardiac standpoint
Causes:
Primary carnitine deficiency is caused by a deficiency in the plasma membrane carnitine transporter, with urinary carnitine wasting resulting from systemic carnitine depletion.
