Stability of amino acids, free and acyl‐carnitine in stored dried blood spots

Abstract

Background Newborn screening of inborn errors of metabolism using tandem mass spectrometry has become a public health strategy in many developed countries. Retrospective analyses using stored dried blood specimens have been limited, mainly due to a lack of biochemical information on the long‐term stability of acylcarnitines and amino acids in stored specimens. We studied the characteristic profiles of the stability of amino acid, free carnitine, and acyl carnitines in dried blood specimens stored in a refrigerator after newborn screening. Methods Dried blood specimens from 198 healthy newborns, which had been stored in a refrigerator at 5 °C after newborn screening, were prospectively subjected to tandem mass spectrometry analyses after 1, 3, 6 months, 1 and 2 years of storage. We also retrospectively re‐analyzed the stored samples from 90 newborns, which had been analyzed and stored at 5 °C for 4 years. Results We found that proline (Pro) and tyrosine (Tyr) were stable for 2 years, and that alanine (Ala), arginine (Arg), and phenylalanine (Phe) decayed with linear regression. The C0 increased during the time‐course of 2 years, whereas most acylcarnitines gradually decayed and some showed a linear correlation. The retrospective analysis of samples stored for 4 years revealed that Ala, Phe, Pro and Tyr were almost stable, leucine (Leu), valine (Val) decayed with linear regression, C0 increased, and C10, C12, C14, C14:1, C16, C18, C18:1 decreased, while maintaining a linear correlation. Conclusions These data suggested that some metabolic parameters from refrigerator‐stored dried blood specimens were applicable for the detection of inborn errors of metabolism.

Tandem Mass Spectrometry Screening for Inborn Errors of Metabolism: Comprehensive Bibliometric Analysis

“…Among the papers on this topic are those from Asia because storage conditions for DBS in hot and humid climates are critical [134,143]. However, the issue of storage conditions for DBS and the development of references and correction factors for metabolites is relevant not only for developing countries due to recent trends in the creation of biobanks and using stored samples for metabolomic studies, including disease prediction and understanding the basic molecular mechanisms of disease development [144][145][146].…”

Important Lessons on Long-Term Stability of Amino Acids in Stored Dried Blood Spots

“…Short-term stability of AA, most often in plasma, has been described earlier [ 10 , 11 , 12 , 13 , 14 ]. However, only a few articles describe long-term stability of AA in DBS [ 15 , 16 , 17 , 18 ]. While most previous studies highlight the conditions that affect long-term metabolite stability (especially high temperatures, high humidity and long storage times), they often lack a description of clinical implications resulting from these findings.…”