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SI UNITS (recommended)


* The SI units is the recommended method of reporting clinical laboratory results

Units of measurement
µmol/L, mg/L, mg/dL, mg/100mL, mg%, µg/mL

L-cystine is a covalently linked dimeric nonessential amino acid formed by the oxidation of cystine. Two molecules of cysteine are joined together by a disulfide bridge to form cystine.

Not considered one of the 20 amino acids, Cystine is a sulfur-containing derivative obtained from oxidation of cysteine amino acid thiol side chains. It functions as an antioxidant and protects tissues against radiation and pollution, slowing the aging process. It also aids protein synthesis. Cystine is abundant in many proteins of skeletal tissues and skin, and found in insulin and digestive enzymes chromotrypsinogen A, papain, and trypsinogen.

Cystine is an oxidized dimeric form of cysteine. It is formed by linking two cysteine residues via a disulfide bond (cys-S-S-cys) between the -SH groups. Cystine is found in high concentrations in the cells of the immune system, skeletal and connective tissues, skin, digestive enzymes, and in hair. Hair and skin are 10-14% cystine. Cystine is the preferred form of cysteine for the synthesis of glutathione in cells involved in the immune function including macrophages and astrocytes. Lymphocytes and neurons prefer cysteine for glutathione production. Optimizing glutathione levels in macrophages and astrocytes with cystine allows these cells to provide cysteine to lymphocytes and neurons directly upon demand.

Lab units Conversion Calculator. Convert Cystine level to µmol/L, mg/L, mg/dL, mg/100mL, mg%, µg/mL. Clinical laboratory units online conversion from conventional or traditional units to Si units. Table of conversion factors for Cystine.