Hyperhomocysteinemia

Excerpt

Homocysteine is an amino acid not supplied by the diet that can be converted into cysteine or recycled into methionine, an essential amino acid, with the aid of specific B vitamins. Homocysteine levels vary between men and women, with a normal range typically between 5 to 15 micromol/L. Hyperhomocysteinemia is when levels exceed 15 micromol/L.

When homocysteine levels are greater than normal limits, it signifies a disruption in the metabolism of homocysteine. Elevated levels of homocysteine have been associated with increased cardiovascular, cerebrovascular, and thromboembolic diseases. While there are clear associations between homocysteine and cerebrovascular disease, the evaluation and treatment remain controversial as studies have shown conflicting results in its effect in lowering risks for cardiovascular and cerebrovascular disease. There has been clear evidence that lowering homocysteine levels decreases cardiovascular risks in patients with homocystinuria, a rare autosomal recessive disorder, which can lead to atherosclerotic disease at a young age. Also, some studies have shown that lowering homocysteine levels can be beneficial in slowing the acceleration of brain atrophy. On the other hand, a meta-analysis by the American Heart Association showed that homocysteine-lowering therapies did not significantly affect averting stroke and have a non-significant impact on coronary heart disease.

Homocysteine levels are generally categorized into three groups: moderate (16 to 30 micromol/L), intermediate (31 to 100 micromol/L), and severe (over 100 micromol/L).