Medical Care
In infants with carnitine deficiency ascertained via newborn screen program, oral carnitine supplementation is followed by a slow increase of plasma carnitine levels. If the infants’ levels reflect maternal primary carnitine deficiency, the rise in plasma levels is fast and this should prompt the work-up towards the diagnosis of maternal primary carnitine deficiency. Guidelines for the management of carnitine deficiency and other fatty acid mitochondrial disorders have been established. [13]
Evaluation for carnitine deficiency may be performed on an outpatient basis. In cases of acute decompensation, inpatient studies may be necessary in the acute phase and following stabilization of the patient.
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 intravenous (IV) initially; adjust infusion rate according to blood glucose concentrations.
IV carnitine restores tissue carnitine concentrations for the transport of fatty acids in the mitochondria. This treatment removes toxic metabolites in the form of carnitine esters that are readily excreted in the urine. The use of IV carnitine should be considered only when the diagnosis of primary carnitine deficiency is entertained or confirmed. The use of IV carnitine in disorders of fatty acid oxidation in which long-chain acylcarnitines accumulate and have the potential of being arrhythmogenic is controversial. IV carnitine may be considered in cases of organic acidemias (eg, isovaleric acidemia, propionic acidemia, methylmalonic acidemia) when oral intake is not feasible.
Consider pharmacological support for cardiomyopathy.
Medical therapy with oral carnitine in primary carnitine deficiency improves fasting ketogenesis, cardiac function, growth, and cognitive performance.
Direct the therapy in secondary carnitine deficiency to replenish carnitine and treat the primary metabolic defect with specific diet and other supplements, such as riboflavin, glycine, or biotin.
Actively avoid periods of fasting in these patients.
Consultations
The following consultations may be indicated:
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Genetic metabolic services
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Nutritionist
Diet
Patients with primary carnitine deficiency requires no special diet as long as they are taking carnitine supplementation and are not faced with situations of stress and starvation. Actively avoid periods of fasting in these patients.
Patients with fatty acid oxidation disorders require a high-carbohydrate fat-restricted diet (30% calories from fat) and must eat frequently.
Prescribe medium-chain triglyceride supplementation in patients with long-chain fatty acid disorders.
Advise use of uncooked cornstarch at bedtime to prevent early morning hypoglycemia after the overnight fast.
Supplementation of essential fatty acids (ie, linoleic acids, linolenic acids) prevents the growth restriction and dermatitis that are associated with fatty acid deficiency.
Consider specific protein-restricted diets in patients with aminoacidopathies and organic acidemias associated with secondary carnitine deficiency.
Activity
Once carnitine supplementation has been instituted for primary carnitine deficiency, cardiac function, strength, and growth improve significantly. No specific recommendations to limit physical activity are indicated if the cardiomyopathy has reverted.
Secondary carnitine deficiency caused by fatty acid oxidation disorders may require tempered or restricted activity in certain cases, including the following:
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Conditions associated with increased risk for rhabdomyolysis and myoglobinuria (eg, carnitine palmitoyltransferase II [CPT-II] deficiency, very long-chain acyl-CoA dehydrogenase [VLCAD] deficiency)
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Conditions in which a cardiomyopathy is present (eg, long-chain 3-hydroxyacyl-CoA dehydrogenase [LCHAD] deficiency, VLCAD deficiency)
Strenuous exercise or activity should be avoided, and frequent snacks and good hydration should be procured with physical activity.
