Most laboratories report normal homocysteine levels in the blood between 4 and 15 micromoles/liter (µmol/L). Any measurement above 15 is considered high. Any measurement below 12 is considered low. Optimal homocysteine levels are below 10 to 12.
Hyperhomocysteinemia has been classified into moderate, intermediate, and severe types based on the level of homocysteine and are:
Elevated homocysteine levels in the body do not cause any symptoms. However, elevated levels of it in the blood have been associated with health risks. Therefore, an elevated homocysteine level may be a risk factor for developing certain diseases and conditions. For example:
While alcoholics tend to be malnourished and lacking in B vitamins , alcohol itself may independently cause homocysteine levels in the blood to rise.
Homocystinuria (meaning elevated homocysteine in the urine) is a rare, inherited disease in which affected persons have abnormally high levels of homocysteine due to abnormal metabolism of the amino acid methionine. This condition is associated several different birth defects including abnormalities of the musculoskeletal system. In infants who have a family history of homocystinuria, early screening for elevated levels may help prevent future illnesses related to this metabolic defect. Moreover, infants and young children who have eye problems such as myopia (nearsightedness ), changes in the lens of the eye, bone abnormalities, or unusual body shape may be screened for elevated homocysteine levels.
Elevated levels of homocysteine are associated with heart attack, stroke, and blood clots. If a person develops any of these diseases and does not have increased risk factors such as smoking, high blood pressure, high cholesterol, or diabetes, then the physician often looks for more unusual causes and risks, including checking homocysteine levels in the blood.
The treatment for homocystinuria is vitamin supplementation with pyridoxine (vitamin B6), vitamin B12, and folic acid. The effects of vitamin treatment may be monitored by routine, scheduled blood tests. However, evidence to support the value of treating elevated blood levels of homocysteine (except in cases of severely high levels) in the general population is lacking. Therefore, it is not recommended that people be treated with vitamins to lower homocysteine levels to prevent vascular disease.
Some patients do not respond to the vitamin supplementation and are considered pyridoxine resistant. A diet low in methionine is recommended in addition to the B vitamins.
Infants blood and urine are often checked for elevated homocysteine levels if they have a family history of the disease, or if they have certain medical conditions including eye lens dislocations, unusual (Marfan type) body shape, mental retardation, or signs of stroke.
Younger adults who have an early heart attack, stroke, or blood clots are often screened for blood clotting abnormalities including homocysteine blood tests.
Homocysteine levels are also often measured when a patient suffers a heart attack or stroke and has no risk factors for that illness (smoking , high blood pressure , high cholesterol , diabetes ).
At present it is not recommended that individuals consuming normal diets with adequate folate levels be screened for elevated homocysteine levels.
There is controversy whether lowering homocysteine levels affects the risk of vascular disease like heart attack and stroke. At present there is no proof to show that lowering these levels has any benefit in terms of disease prevention, so treatment aimed at lowering blood homocysteine levels is not recommended for most people who do not have severe hyperhomocysteinemia. Some studies suggest that lowering homocysteine levels may decrease the risk of stroke. However, while the overall risk of stroke decreased in these studies, the severity of the stroke and the amount of disability were not affected. More importantly, medications that affect platelet function such as aspirin, clopidogrel (Plavix), and aspirin-dipyridamole (Aggrenox) are recommended and are effective as secondary stroke prevention medications. There is uncertainty whether the risk of heart disease is affected.
Pernicious anemia, or vitamin B-12 deficiency, is a type of anemia that's caused by the body's inability to absorb vitamin B-12 from the gut. Symptoms take many years to appear, and when they do you may experience clumsiness, lack of coordination, and personality changes. One blood test used to diagnose this condition is a homocysteine blood test since elevated levels of homocysteine is characteristic of vitamin B-12 deficiency.
