Homocystine Unit Converter

Homocystine is the oxidized form of homocysteine, formed when two homocysteine molecules link together through a disulfide bond. It appears in both blood and urine as part of a quantitative amino acid profile.

In healthy individuals, homocystine is normally undetectable or present only in trace amounts. Elevated homocystine in urine (homocystinuria) is a hallmark finding in disorders of homocysteine metabolism, most notably classic homocystinuria caused by cystathionine beta-synthase (CBS) deficiency.

Homocystine is distinct from total homocysteine, which includes free reduced homocysteine, protein-bound forms, and mixed disulfides with cysteine. The presence of homocystine in urine specifically suggests a significant elevation in circulating homocysteine.

Homocystine forms spontaneously in the blood and urine when two homocysteine molecules undergo oxidation. Homocysteine itself is produced in every cell of the body as a byproduct of methionine metabolism, primarily in the liver.