Last reviewed 01/2018

  • homocysteine is produced by the demethylation of methionine, an essential amino acid
  • homocystinuria - due to a lack of the enzyme cystathione- beta-synthase which usually convert methionine to cystathione. This results in accumulation of the metabolic intermediates homocysteine and homocystine (referred to as homocyst(e)ine). Homocystine is excreted in the urine
  • homocystinuria is associated with a high risk of thromboembolic events including stroke and myocardial infarction in early adolescence or even in childhood
  • evidence suggests that moderately elevated homocysteine plasma levels (moderate hyperhomocysteinaemia) are common in the general population - see menu item


  • Lancet (1999), 354, 407-413.
  • British Heart Foundation, Factfile 3/2000.