Carnitine Levels in Skeletal Muscle, Blood, and Urine in Patients with Primary Carnitine Deficiency During Intermission of L-Carnitine Supplementation

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Background: Primary carnitine deficiency (PCD) is a disorder of fatty acid oxidation with a high prevalence in the Faroe Islands. Only patients homozygous for the c.95A>G (p.N32S) mutation have displayed severe symptoms in the Faroese patient cohort. In this study, we investigated carnitine levels in skeletal muscle, plasma, and urine as well as renal elimination kinetics before and after intermission with L-carnitine in patients homozygous for c.95A>G. Methods: Five male patients homozygous for c.95A>G were included. Regular L-carnitine supplementation was stopped and the patients were observed during five days. Blood and urine were collected throughout the study. Skeletal muscle biopsies were obtained at 0, 48, and 96 h. Results: Mean skeletal muscle free carnitine before discontinuation of L-carnitine was low, 158 nmol/g (SD 47.4) or 5.4% of normal. Mean free carnitine in plasma (fC0) dropped from 38.7 (SD 20.4) to 6.3 (SD 1.7) μmol/L within 96 h (p < 0.05). Mean T 1/2 following oral supplementation was approximately 9 h. Renal reabsorption of filtered carnitine following oral supplementation was 23%. The level of mean free carnitine excreted in urine correlated (R (2) = 0.78, p < 0.01) with fC0 in plasma. Conclusion: Patients homozygous for the c.95A>G mutation demonstrated limited skeletal muscle carnitine stores despite long-term high-dosage L-carnitine supplementation. Exacerbated renal excretion resulted in a short T 1/2 in plasma carnitine following the last oral dose of L-carnitine. Thus a treatment strategy of minimum three daily separate doses of L-carnitine is recommended, while intermission with L-carnitine treatment might prove detrimental.

Original languageEnglish
Title of host publicationJIMD Reports
EditorsJohannes Zschocke, Matthias Baumgartner, Eva Morava, Marc Patterson, Shamima Rahman, Verena Peters
Number of pages9
Volume20
Place of PublicationBerlin
PublisherSpringer
Publication date10 Feb 2015
Pages103-111
ISBN (Print)978-3-662-46699-5
ISBN (Electronic)978-3-662-46700-8
DOIs
Publication statusPublished - 10 Feb 2015
SeriesJIMD Reports
ISSN2192-8304

ID: 161364676