investigations

Last reviewed 01/2018

Investigations:

• plasma methionine and homocystine levels are elevated
• homocystine is excreted in the urine
• plasma cystine levels are reduced
• positive urine cyanide-nitroprusside test

Urine or serum samples should be rapidly deproteinised prevent the formation of disulphide bonds between proteins and homocyst(e)ine.

Ref: Stantbury JB et al (1983). The Metabolic Basis of Inherited Disease, 5th edn. McGraw-Hill.