Pilot Experience with an External Quality Assurance Scheme for Acylcarnitines in Plasma/Serum
- 362 Downloads
The analysis of acylcarnitines (AC) in plasma/serum is established as a useful test for the biochemical diagnosis and the monitoring of treatment of organic acidurias and fatty acid oxidation defects. External quality assurance (EQA) for qualitative and quantitative AC is offered by ERNDIM and CDC in dried blood spots but not in plasma/serum samples. A pilot interlaboratory comparison between 14 European laboratories was performed over 3 years using serum/plasma samples from patients with an established diagnosis of an organic aciduria or fatty acid oxidation defect. Twenty-three different samples with a short clinical description were circulated. Participants were asked to specify the method used to analyze diagnostic AC, to give quantitative data for diagnostic AC with the corresponding reference values, possible diagnosis, and advice for further investigations.
Although the reference and pathological concentrations of AC varied among laboratories, elevated marker AC for propionic acidemia, isovaleric acidemia, medium-chain acyl-CoA dehydrogenase, very long-chain acyl-CoA dehydrogenase, and multiple acyl-CoA dehydrogenase deficiencies were correctly identified by all participants allowing the diagnosis of these diseases. Conversely, the increased concentrations of dicarboxylic AC were not always identified, and therefore the correct diagnosis was not reach by some participants, as exemplified in cases of malonic aciduria and 3-hydroxy-3-methylglutaryl-CoA lyase deficiency. Misinterpretation occurred in those laboratories that used multiple-reaction monitoring acquisition mode, did not derivatize, or did not separate isomers. However, some of these laboratories suggested further analyses to clarify the diagnosis.
This pilot experience highlights the importance of an EQA scheme for AC in plasma.
KeywordsAcylcarnitines External quality assurance Fatty acid oxidation defects Organic acidurias
We thank Mrs. A Sánchez for technical assistance in preparing the samples. We are grateful to the Scientific Advisory Board of ERNDIM for support and helpful discussions.
- Ferrer I, Ruiz-Sala P, Vicente Y, Merinero B, Perez-Cerda C, Ugarte M (2007) Separation and identification of plasma short-chain acylcarnitine isomers by HPLC/MS/MS for the differential diagnosis of fatty acid oxidation defects and organic acidemias. J Chromatogr B Analyt Technol Biomed Life Sci 860:121–126CrossRefPubMedGoogle Scholar
- McHugh D, Cameron CA, Abdenur JE, Abdulrahman M, Adair O, Al Nuaimi SA, Ahlman H, Allen JJ, Antonozzi I, Archer S, Au S, Auray-Blais C, Baker M, Bamforth F, Beckmann K, Pino GB, Berberich SL, Binard R, Boemer F, Bonham J, Breen NN, Bryant SC, Caggana M, Caldwell SG, Camilot M, Campbell C, Carducci C, Bryant SC, Caggana M, Caldwell SG, Camilot M, Campbell C, Carducci C, Cariappa R, Carlisle C, Caruso U, Cassanello M, Castilla AM, Ramos DE, Chakraborty P, Chandrasekar R, Ramos AC, Cheillan D, Chien YH, Childs TA, Chrastina P, Sica YC, de Juan JA, Colandre ME, Espinoza VC, Corso G, Currier R, Cyr D, Czuczy N, D’Apolito O, Davis T, de Sain-Van der Velden MG, Delgado Pecellin C, Di Gangi IM, Di Stefano CM, Dotsikas Y, Downing M, Downs SM, Dy B, Dymerski M, Rueda I, Elvers B, Eaton R, Eckerd BM, El Mougy F, Eroh S, Espada M, Evans C, Fawbush S, Fijolek KF, Fisher L, Franzson L, Frazier DM, Garcia LR, Bermejo MS, Gavrilov D, Gerace R, Giordano G, Irazabal YG, Greed LC, Grier R, Grycki E, Gu X, Gulamali-Majid F, Hagar AF, Han L, Hannon WH, Haslip C, Hassan FA, He M, Hietala A, Himstedt L, Hoffman GL, Hoffman W, Hoggatt P et al (2011) Clinical validation of cutoff target ranges in newborn screening of metabolic disorders by tandem mass spectrometry: a worldwide collaborative project. Genet Med 13:230–254CrossRefPubMedGoogle Scholar