Jaafar Sadeq Abdulridha - Department of Clinical Biochemistry, Mashhad University of Medical Sciences, Mashhad, Iran.
Baratali Mashkani - Department of Clinical Biochemistry, Mashhad University of Medical Sciences, Mashhad, Iran.
Amin Alaei - Department of Medical Laboratory Science, Varastegan Institute for Medical Sciences, Mashhad, Iran & Division of Metabolic Disorder, Pardis Clinical and Genetic Laboratory, Mashhad, Iran & Research Committee, Department of Medical Laboratory Science, Vara
Mostafa Boskabadi - School of Health, Mashhad University of Medical Sciences, Mashhad, Iran.
Abdolreza Varasteh - Department of Medical Laboratory Science, Varastegan Institute for Medical Sciences, Mashhad, Iran & Division of Metabolic Disorder, Pardis Clinical and Genetic Laboratory, Mashhad, Iran.
Fatemeh Keyfi - Department of Medical Laboratory Science, Varastegan Institute for Medical Sciences, Mashhad, Iran & Division of Metabolic Disorder, Pardis Clinical and Genetic Laboratory, Mashhad, Iran.

Background: Acylcarnitine is one of the crucial markers of fatty acid metabolism, and examination of their level in infants can reveal several Inherited Metabolic Disorders (IDM) or Inborn errors of Metabolism (IEM). Because of the great importance of hereditary, metabolic, and other inherited disorders early diagnosis before the appearance of clinical symptoms, this study was carried out to establish a reference range for carnitine analytes and to identify acylcarnitine profiles in normal weight neonatal dried blood spots (DBS) specimens. Methods: By using liquid chromatography tandem mass spectrometry (LC-MS/MS) for neonatal screening and eventually the examination and analysis of LC-MS/MS results, ۳۴ acylcarnitine derivatives were identified. Results: The normal range for acylcarnitine analytes with carbon numbers ranging from zero to ۱۸, both main and the branched ones, were ultimately measured. Afterward, they were compared with the results of some other diagnostic laboratories to be verified. Conclusion: This study differed from the other findings, which could be due to diversity in population and work methods. However, the reference range of most acylcarnitine derivatives in Tehran closely aligned with this study's findings.

Acylcarnitines, Dried Blood Spot, LC-MS/MS, Newborn screening, Reference range.