Cystathionine is a thioether and an intermediate metabolite of the transsulfuration pathway where homocysteine is converted to cysteine. Both the enzymes responsible for cystathionine formation (cystathionine beta-synthase) and degradation (cystathionine gamma-lyase) are dependent on vitamin B6 (pyridoxal 5′-phosphate).
Cystathionine increases moderately in conditions associated with elevated tHcy (folate and cobalamin deficiencies), markedly in patients with the inborn error, cystathioninuria/cystathionase deficiency, and decreases moderately after intake of vitamin B6 supplements.
Assessment of homocysteine and one-carbon status. Diagnosis of cystathioninuria/cystathionase deficiency. Cystathionine increases during B6-deficiency.
Patient/subject: Prandial status affects concentration, which increases up to 3-fold after a protein rich meal.
Matrix: Serum or EDTA plasma.
Volume: Volume: Minimum volume is 50 µL, but 200 µL is optimal and allows reanalysis.
Preparation and stability: Cystathionine is stable.
Reported values: 0.07-0.55 µmol/L
Intraclass correlation coefficient (ICC): 0.63.
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. Midttun, O., Kvalheim, G., and Ueland, P.M. (2013). High-throughput, low-volume, multianalyte quantification of plasma metabolites related to one-carbon metabolism using HPLC-MS/MS. Anal Bioanal Chem 405, 2009-017.
3. Midttun, O., Hustad, S., and Ueland, P.M. (2009). Quantitative profiling of biomarkers related to B-vitamin status, tryptophan metabolism and inflammation in human plasma by liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Sp 23, 1371-79.