Abstract
Patients with organic acidemias may have low plasma free carnitine concentrations and urinary acylcarnitines may be elevated. A concomitant muscular carnitine deficiency has been thought to contribute to the frequently observed hypotonia in these patients. Oral supplementation with carnitine could restore normal carnitine concentrations and promote the removal of ‘toxic’ short-chain fatty acids as acylcarnitines. We analyzed urinary acylcarnitines by means of ammonia desorption chemical ionization mass spectrometry and also by 500 MHz 1H-nuclear magnetic resonance spectroscopy. The latter technique gives accurate information about the structures of the carnitine esters; their molecular weights are derived from the mass spectrometric measurements. Various urinary acylcarnitines were identified: propionylcarnitine in propionic acidemia and methylmalonic acidemia, isovalerylcarnitine in isovaleric acidemia, octanoylcarnitine in medium-chain acyl-CoA dehydrogenase deficiency. Isovalerylcarnitine increased considerably in a patient with isovaleric acidemia after oral supplementation with carnitine (lg/day), but it did not reach the level of that of isovalerylglycine. The amount of propionylcarnitine in patients with propionic acidemia was much lower than that of other propionyl-CoA metabolites such as methylcitrate. In general carnitine supplementation did not prevent metabolic decompensation, but resulted in normalization of plasma free carnitine. A positive effect on the muscle tone was observed in one patient.
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Duran, M., Dorland, L. & Wadman, S. URINARY ACYLCARNITINES IN VARIOUS ORGANIC ACIDEMIAS ANALYZED BY MASS SPECTROMETRY AND H-NUCLEAR MAGNETIC RESONANCE SPECTROSCOPE. Pediatr Res 19, 1086 (1985). https://doi.org/10.1203/00006450-198510000-00108
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DOI: https://doi.org/10.1203/00006450-198510000-00108