Hyperhomocysteinemia refers to the condition where there is greater than 15 micromol/L of homocysteine in the blood. This condition is present in a wide range of diseases, and in many cases, it is an independent risk factor for more serious medical conditions.
Hyperhomocysteinemia is a trigger for many diseases, such as atherosclerosis, congestive heart failure, age-related macular degeneration, Alzheimer's disease and hearing loss. There are many studies showing a positive relationship between homocysteine level and various symptoms.
Homocysteine is an amino acid. Vitamins B12, B6 and folate break down homocysteine to create other chemicals your body needs. High homocysteine levels may mean you have a vitamin deficiency. Without treatment, elevated homocysteine increases your risks for dementia, heart disease and stroke.
Vitamin B12 deficiency leads to a serum build-up of methylmalonic acid. Deficiency of vitamin B12 or folic acid can lead to increased homocysteine levels.
Normal" levels of homocysteine range from 5 to 15 micromoles per liter (? mol/L). People with levels of 50 or higher are at increased risk of cardiovascular events. A very few families have genetic defects that raise their levels to well over 100.Hyperhomocysteinemia, or increased levels of the amino acid, homocysteine, affects about 5% of the general population. Approximately 13-47% of people with symptoms of heart disease have this condition. Mild to moderately high levels of homocysteine is a single risk factor for stroke, heart attack, peripheral arterial disease, and narrowing of the extracranial carotid artery.
High levels of homocysteine are also associated with enzyme defects or decreased amounts of folate or vitamin B6, particularly in the elderly. Mild or moderate hyperhomocysteinemia has been associated with venous blood clots in the young and recurrent blood clots. The condition also has been found in approximately 10% of patients who experience their first episode of a venous blood clot.
Several inherited or acquired conditions may lead to an increase in homocysteine levels.
INHERITED CAUSES
Inherited causes of hyperhomocysteinemia include low levels of an enzyme needed to change homocysteine into cysteine. In turn, this increases the risk of a clotting event. Mild inherited hyperhomocysteinemia has been found in 19% of cases of venous clotting in children.
ACQUIRED CAUSES
Acquired causes of hyperhomocysteinemia include:
Advanced age
Tobacco use
Coffee intake
Low levels of folate in the diet
Low intake of vitamin B
Increased homocysteine levels are also associated with diabetes mellitus, cancers, low level of thyroid function, lupus, and inflammatory bowel disease; and are a side-effect of certain medications such as cholesterol-lowering agents, metformin, methotrexate, anticonvulsants, theophylline, and levodopa.MTHFR gene mutations are also one of the potential causes of homocystinuria, which is a genetic condition that affects how the body processes the building blocks of amino acids, such as folate and B vitamins.
Other genes that can be involved include:
CBS
MTR
MTRR
MMADHC
Worldwide, around 1 in 200,000–335,000 people have homocystinuria. Many states test for the most common type of homocystinuria at birth.The following nutrients may help to lower homocysteine levels:
betaine
folic acid
vitamin B2
vitamin B6
vitamin B12
zinc
People with certain genetic differences or homocystinuria may need to take supplements and also follow a diet that limits protein throughout their lives.Nutrients involved in the metabolism of homocysteine include folate, vitamin B12, vitamin B6, riboflavin, and choline. Although supplementation with folate, vitamin B6, and vitamin B12 successfully lowers homocysteine concentration in the blood, no significant effect on CVD risk has been demonstrated.
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