Establishment of Age Specific Reference Interval for Aminoacids and Acylcarnitine in Dried Blood Spot by Tandem Mass Spectrometry

• Published in: Indian journal of clinical biochemistry 2024-04, Vol.39 (2), p.233-240
• Main Authors: Kumar, B. Vinodh, Kadiyala, Pramila, Ponmalar, P., Pauline, Leema, Srinivasan, S.
• Format: Article
• Language: English
• Subjects: Acetyl-L-carnitine; Aciduria; Acyl-CoA dehydrogenase; Age; Age composition; Amino acids; Biochemistry; Biomedical and Life Sciences; Blood; Chemistry/Food Science; Citrulline; Dehydrogenases; Deoxyadenosine; Fatty acids; Homocystinuria; Inborn errors of metabolism; Life Sciences; Maple syrup urine disease; Mass spectrometry; Mass spectroscopy; Medical screening; Methionine; Microbiology; Original Research Article; Ornithine; Oxidation; Pathology; Phenylketonuria; Propionic acidemia; Protein deficiency; Scientific imaging; Valine; Very long chain acyl-CoA dehydrogenase
• ISSN: 0970-1915; 0974-0422
• DOI: 10.1007/s12291-023-01128-1

The Extended Screening for Inborn Errors of Metabolism is done for aminoacidopathies, fatty acid oxidation disorders and organic acid disorders. In a single dried blood spot, the tandem mass spectrometry is capable of measuring multiple analytes like amino acids, acylcarnitines, nucleosides, succinylacetone and lysophosphatidylcholines. This study was proposed to establish age specific reference internal for aminoacids and acylcartinitine in dried blood spot by tandem mass spectrometry. A total of 480 apparently healthy children were enrolled for the study and sub classified into four groups as follows: Group A: 0–1 month, Group B: 1 month–1 year, Group C: 1–5 year and Group D: 5–12 years each having 120 participants. Sample size were calculated as per CLSI approved guidelines. Tables 1 and 2 presents the age-specific percentile distribution of aminoacids and acylcarnitines established from healthy subjects as per rank-based method recommended by the IFCC and CLSI. Tables 3 , 4 and 5 presents the cut-off values of primary and secondary marker/ratios for screening of aminoacidopathies, fatty acid oxidation disorders and organic acid disorders respectively. As a general principle, the interpretation of extended newborn screening results should be based on age specific cut-off established by the laboratory for primary analyte concentration and secondary analyte concentration/ ratios. This study was useful in establishing age specific cut-off values for various amino acids and acylcarnitines in South Indian population. Table 1 Age-specific percentile distribution of aminoacids Study groups Group A (μmol/L) Group B (μmol/L) Group C (μmol/L) Group D (μmol/L) Percentile 1 2.5 50 97.5 99 1 2.5 50 97.5 99 1 2.5 50 97.5 99 1 2.5 50 97.5 99 Glycine 44.00 50.00 361.85 745.00 840.00 76.00 81.00 351.41 705.00 820.00 88.00 92.00 383.00 620.00 785.00 109.00 115.00 397.74 600.00 790.00 Alanine 66.00 72.00 325.95 570.00 620.00 66.00 72.00 325.82 580.00 623.00 91.00 99.00 323.40 480.00 514.00 112.00 134.00 355.43 510.00 536.00 ASA 0.00 0.02 0.87 1.20 1.43 0.00 0.00 0.50 0.82 1.15 0.00 0.01 0.55 0.64 0.93 0.00 0.01 0.57 0.72 0.98 Leucine 24.00 33.52 120.84 270.00 300.00 23.00 33.78 113.42 264.00 300.00 44.00 52.01 110.43 223.00 250.00 42.00 52.76 118.91 224.00 250.00 Methionine 0.00 1.00 18.13 37.79 42.00 0.00 1.16 19.10 38.68 44.00 2.21 6.93 18.86 36.79 39.00 2.56 5.36 17.37 35.56 39.00 Ornithine 19.57 21.34 121.49 239.00 257.00 19.00 18.27 125.46 235.00 260.00 18.00 21.91 1