Hyperhomocysteinemia
| Hyperhomocysteinemia | |
|---|---|
 |
|
| Total plasma homocysteine | |
| Classification and external resources | |
| ICD-9-CM | 270.4 |
| DiseasesDB | 29853 |
| eMedicine | neuro/578 |
Hyperhomocysteinemia or hyperhomocysteinaemia is a medical condition characterized by an abnormally high level of homocysteine in the blood, conventionally described as above 15 µmol/L.
As a consequence of the biochemical reactions in which homocysteine is involved, deficiencies of vitamin B6, folic acid (vitamin B9), and vitamin B12 can lead to high homocysteine levels.
Hyperhomocysteinemia is typically managed with vitamin B6, vitamin B9 and vitamin B12 supplementation. Supplements of these vitamins; however, do not change outcomes.
Elevated levels of homocysteine have been associated with a number of disease states.
Elevated homocysteine is a known risk factor for cardiovascular disease and thrombosis. It has also been shown to be associated with microalbuminuria which is a strong indicator of the risk of future cardiovascular disease and renal dysfunction. Homocysteine degrades and inhibits the formation of the three main structural components of arteries: collagen, elastin and proteoglycans. In proteins, homocysteine permanently degrades cysteine disulfide bridges and lysine amino acid residues, affecting structure and function.
Evidence exists linking elevated homocysteine levels and Alzheimer's disease. There is also evidence that elevated homocysteine levels and low levels of vitamin B6 and B12 are risk factors for mild cognitive impairment and dementia. Oxidative stress induced by homocysteine may also play a role in schizophrenia.
Elevated levels of homocysteine have also been linked to increased fractures in elderly persons. Homocysteine auto-oxidizes and reacts with reactive oxygen intermediates, damaging endothelial cells and increasing the risk of thrombus formation.
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