Method(s): GC-MS/MS (1).
What is measured: Ornithine (Orn), aspartic acid (Asp), glutamic acid (Glu), lysine (Lys), alanine acid (Ala), phenylalanine (Phe), isoleucine (Ile), leucine (Leu), proline (Pro), valine (Val), asparagine (Asn), glutamine (Gln), threonine (Thr), and tyrosine (Tyr).
Performance of the assay (GC-MS/MS)
Lower limit of detection (LOD): 0.4-1.2 (10) µmol/L.
Within-day CV: 1.5-2.7 %; between-day CV: 1.7-4 %.
Assessment of cardiovascular risk and risk of diabetes type 2. Branched chain amino acids (BCAA; Leu, Ile and Val) are associated with insulin resistance, diabetes type 2, cardiovascular disease and early kidney disease (2, 3), and the valine catabolites, 3-hydroxyisobutyrate (3HIB) is belived to play a key role in the development of insulin resistance (3).
Specimen, collection and processing
Patient/subject: Prandial status affects concentration, which increases slightly after a protein rich meal.
Matrix: Serum or EDTA plasma.
Volume: Minimum volume is 50 µL, but 200 µL is optimal and allows reanalysis.
Preparation and stability: Most amino acids are stable.
Transportation; for general instruction on transportation, click here.
Frozen, on dry ice.
Reported values, interpretation
Reported values: Orn: 30-90 µmol/L; Asp: 0-26 µmol/L; Glu: 20-140 µmol/L; Lys: 120-290 µmol/L; Ala: 230-510 µmol/L; Phe: 26-85 µmol/L; Ile: 40-140 µmol/L; Leu: 70-170 µmol/L; Pro: 110-360 µmol/L; Val: 150-350 µmol/L; Asn: 20-130 µmol/L; Gln: 390-700 µmol/L; Thr: 70-240 µmol/L; Tyr: 40-110 µmol/L.
Intraclass correlation coefficient (ICC): na.
1. Midttun, Ø., McCann, A., Aarseth, O., Krokeide, M., Kvalheim, G., Meyer, K., and Ueland, P.M. (2016). Combined measurement of 6 fat-soluble vitamins and 26 water-soluble functional vitamin markers and amino acids in 50 μL of serum or plasma by high-throughput mass spectrometry. Anal Chem 88, 10427-436.
2. Lynch, C.J., and Adams, S.H. (2014). Branched-chain amino acids in metabolic signalling and insulin resistance. Nat Rev Endocrinol 10, 723-736.
3. Arany, Z., and Neinast, M. (2018). Branched chain amino acids in metabolic disease. Curr Diab Rep 18, 76.