Long-Term Stability of Amino Acids and Acylcarnitines in Dried Blood Spots

Dried blood filter cards, collected for newborn screening, are often stored for long periods of time. They may be suitable for the retrospective diagnosis of inborn errors of metabolism, but no data are currently available on the long-term stability of amino acids and acylcarnitine species. We analy...

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Bibliographic Details
Published in:Clinical chemistry (Baltimore, Md.) Md.), 2007-04, Vol.53 (4), p.717-722
Main Authors: Strnadova, Kristina Anna, Holub, Margareta, Muhl, Adolf, Heinze, Georg, Ratschmann, Rene, Mascher, Hermann, Stockler-Ipsiroglu, Sylvia, Waldhauser, Franz, Votava, Felix, Lebl, Jan, Bodamer, Olaf A
Format: Article
Language:English
Subjects:
Amino Acids - blood
Analytical, structural and metabolic biochemistry
Biological and medical sciences
Blood Specimen Collection
Carnitine - analogs & derivatives
Carnitine - blood
Fatty acids
Fundamental and applied biological sciences. Psychology
Genetic counseling
Humans
Infant, Newborn
Investigative techniques, diagnostic techniques (general aspects)
Linear Models
Medical diagnosis
Medical sciences
Medical screening
Metabolism
Metabolism, Inborn Errors - diagnosis
Models, Biological
Neonatal Screening - methods
Temperature
Time Factors
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Summary:Dried blood filter cards, collected for newborn screening, are often stored for long periods of time. They may be suitable for the retrospective diagnosis of inborn errors of metabolism, but no data are currently available on the long-term stability of amino acids and acylcarnitine species. We analyzed amino acids and acylcarnitines by tandem mass spectrometry in 660 anonymous, randomly selected filter cards from 1989 through 2004. We assessed long-term stability of metabolites by linear regression and estimated annual decrease of concentration for each metabolite. Concentrations of free carnitine increased by 7.6% per year during the first 5 years of storage and decreased by 1.4% per year thereafter. Alanine, arginine, leucine, methionine, and phenylalanine decreased by 6.5%, 3.3%, 3.1%, 7.3%, and 5.7% per year, respectively. Acetylcarnitine, propionylcarnitine, citrulline, glycine, and ornithine decreased by 18.5%, 27.4%, 8.1%, 14.7%, and 16.3% per year during the first 5 years, respectively; thereafter the decline was more gradual. Tyrosine decreased by 1.7% per year during the first 5 years and 7.9% per year thereafter. We could not analyze medium- and long-chain acylcarnitine species because of low physiological concentrations. Estimation of the annual decrease of metabolites may allow for the retrospective diagnosis of inborn errors of metabolism in filter cards that have been stored for long periods of time.
ISSN:0009-9147
1530-8561
DOI:10.1373/clinchem.2006.076679