Cystine is formed from the oxidation of cysteine, or from the degradation of glutathione oxidation products. It is two cysteines linked together with a disulfide bond.
The urine FMV amino acid test reports cysteine and cystine separately. The plasma amino acid test combines both cysteine and cystine as one biomarker.
References:
- Go YM, Jones DP. Redox theory of aging: implications for health and disease. Clin Sci. 2017;131(14):1669-1688.
- Dall’Acqua S, Stocchero M, Boschiero I, et al. New findings on the in vivo antioxidant activity of Curcuma longa extract by an integrated (1)H NMR and HPLC-MS metabolomic approach. Fitoterapia. 2016;109:125-131.
- Woodard LE, Welch RC, Veach RA, et al. Metabolic consequences of cystinuria. BMC Nephrol. 2019;20(1):227.
- Brantley MA, Jr., Osborn MP, Sanders BJ, et al. The short-term effects of antioxidant and zinc supplements on oxidative stress biomarker levels in plasma: a pilot investigation. Am J Ophthalmol. 2012;153(6):1104-1109.e1102.
- Hopkins MH, Fedirko V, Jones DP, Terry PD, Bostick RM. Antioxidant micronutrients and biomarkers of oxidative stress and inflammation in colorectal adenoma patients: results from a randomized, controlled clinical trial. Cancer Epidemiol Biomarkers Prev. 2010;19(3):850 858.
- Leslie SW, Sajjad H, Nazzal L. Renal Calculi (Cystinuria, Cystine Stones). In: StatPearls. Treasure Island (FL): StatPearls Publishing LLC.;2020
- Birwe H, Schneeberger W, Hesse A. Investigations of the efficacy of ascorbic acid therapy in cystinuria. Urolog Res. 1991;19(3):199-201.
- Brundig P, Borner RH, Berg W, et al. [Possibilities and limits in the treatment of cystine calculus diathesis with high-dose ascorbic acid. Results of a combined study with 17 patients]. Zeitschrift Urol Nephrol. 1986;79(3):137-146.
- Lux B, May P. Long-term observation of young cystinuric patients under ascorbic acid therapy. Urolog Internat. 1983;38(2):91-94.
- Asper R, Schmucki O. [Cystinuria therapy by ascorbic acid (author’s transl)]. Urolog Internat. 1982;37(2):91-109.
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