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Infantile idiopathic myopathic carnitine deficiency: treatment with L-carnitine
1Pediatric Neurology Unit, Hadassah University Hospital, Mt. Scopus Jerusalem, Israel.
Insights
Infants with idiopathic carnitine deficiency showed improved muscle tone and motor function after L-carnitine therapy. Six months of treatment benefited most, but longer therapy may be needed for full recovery.
Area of Science:
- Biochemistry
- Pediatric Neurology
- Metabolic Disorders
Background:
- Idiopathic myopathic carnitine deficiency presents as hypotonia and motor delay in infants.
- Carnitine deficiency impairs muscle energy metabolism, leading to weakness and developmental delays.
- Secondary causes of carnitine deficiency were excluded in affected infants.
Purpose of the Study:
- To evaluate the efficacy of L-carnitine therapy in infants with idiopathic myopathic carnitine deficiency.
- To assess changes in muscle carnitine levels and clinical outcomes following treatment.
- To determine optimal treatment duration and dosage for achieving full recovery.
Main Methods:
- Nine infants diagnosed with idiopathic myopathic carnitine deficiency were enrolled.
- Muscle carnitine concentrations were measured before and after L-carnitine supplementation.
- Clinical assessments of muscle tone and motor function were performed at baseline and follow-up.
Main Results:
- Muscle carnitine levels were significantly lower than normal in all patients.
- L-carnitine therapy (100 mg/kg/day) led to clinical improvement in 7 of 9 infants within 6 months.
- Muscle carnitine concentrations increased, but normalization was achieved in only 2 patients.
Conclusions:
- L-carnitine supplementation is beneficial for infants with idiopathic myopathic carnitine deficiency, improving muscle function.
- While 6 months of therapy shows promise, extended treatment duration may be necessary for complete recovery.
- Maintaining a dosage of at least 100 mg/kg/day is recommended for L-carnitine therapy in this condition.
Abstract:
A series of 9 infants, ranging in age from 3 months to 5 years (average: 2 years), suffered from idiopathic myopathic carnitine deficiency presenting as hypotonia and motor delay. Secondary carnitine deficiency was eliminated by appropriate tests. Muscle carnitine concentration ranged from 2.3-7.1 nmol/mg non-collagen protein (NCP; average: 4.87 nmol/mg NCP; normal: 22 +/- 6 nmol/mg NCP). Lipid accumulation in muscle was observed in 2 of 8 patients. Therapy with L-carnitine (100 mg/kg/day in most patients) was given with clinical and laboratory follow-up 6 months later. In 7 of 9 patients, muscle tone and motor function improved. Muscle carnitine concentration increased to a range of 2.7-23.4 nmol/mg (average: 12.27 nmol/mg). In some patients the muscle carnitine content multiplied by a factor of 3-4, but carnitine concentration reached the normal range in only 2 patients. Most infants with idiopathic carnitine deficiency did benefit from 6 months of therapy; however, in order to achieve full recovery the duration of therapy should probably continue for longer periods, with a dose of not less than 100 mg/kg/day.