title: Acylcarnitine profiles during carnitine loading and fasting tests in a Japanese patient with medium-chain acyl-CoA dehydrogenase deficiency.
abstract: Medium-chain acyl-CoA dehydrogenase deficiency (MCADD) is rare among Asian individuals, and the clinical course and biochemical findings remain unclear. We report herein a 3-year-old Japanese girl with MCADD. The diagnosis was suggested by acylcarnitine profiles and confirmed by enzyme activity and genetic analysis after clinical presentation. Our described method with high-performance liquid chromatography/tandem mass spectrometry allows quantification of levels of n-octanoylcarnitine (C8-N) and other isomers (e.g. valproylcarnitine). We examined the patient's acylcarnitine profiles in serum and urine samples during carnitine loading and 14-hr fasting tests with/without carnitine supplementation. Under hypocarnitinemia, serum level of C8-N was 0.16 micromol/l and C8-N/decanoylcarnitine (C10) ratio was 1.8, which did not correspond to the diagnostic criteria for MCADD. However, intravenous carnitine loading test (100 mg/kg/day for 3 days and 50 mg/kg/day for 1 day) led to increased serum C8-N levels and urinary excretion was obvious, strongly suggesting MCADD. In the fasting test with carnitine supplementation, marked production of acylcarnitines (C8-N > C2 >> C6 > C10) was found, compared to the fasting test without carnitine supplementation. These results indicate that carnitine supplementation may be useful for detoxification of accumulated acylcarnitines even in an asymptomatic state. Moreover, the one-point examination for serum C8-N level and/or C8-N/C10 ratio may make the diagnosis of MCADD difficult, particularly in the presence of significant hypocarnitinemia. To avoid this pitfall, attention should be given to serum levels of free carnitine, and carnitine loading may be demanded in hypocarnitinemia.
authors: Department of Pediatrics and Neonatology, Nagoya City University, Graduate School of Medical Science, Nagoya, Japan.
authors: Kyoko
authors: K
authors: Yokoi
authors: Tetsuya
authors: T
authors: Ito
authors: Yasuhiro
authors: Y
authors: Maeda
authors: Yoko
authors: Y
authors: Nakajima
authors: Akihito
authors: A
authors: Ueta
authors: Takayasu
authors: T
authors: Nomura
authors: Norihisa
authors: N
authors: Koyama
authors: Ineko
authors: I
authors: Kato
authors: Satoshi
authors: S
authors: Suzuki
authors: Yukihisa
authors: Y
authors: Kurono
authors: Naruji
authors: N
authors: Sugiyama
authors: Hajime
authors: H
authors: Togari
mesh_terms: D042964:Acyl-CoA Dehydrogenase / Q000172:deficiency*; D044466:Asian People; D001786:Blood Glucose; D002331:Carnitine / Q000031:analogs & derivatives* / Q000097:blood / Q000652:urine; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D003955:Diagnostic Tests, Routine / Q000379:methods*; D005215:Fasting; D005260:Female; D006801:Humans; D007564:Japan; D008052:Lipid Metabolism, Inborn Errors / Q000201:enzymology*
chemical_list: D001786:Blood Glucose; C116917:acylcarnitine; D042964:Acyl-CoA Dehydrogenase; D002331:Carnitine