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Symptoms and Signs of Homocysteine Blood Test

Doctor's Notes on Homocysteine,Test, 6 Symptoms, Levels, and Function

Homocysteine is an amino acid; normal levels in the blood vary between 4-15 micromoles/liter. There are no signs or symptoms of elevated, normal or low levels; however, high levels have been associated with heart disease, cardiovascular disease, angina, dementia, Alzheimer's disease, miscarriage, premature birth, maternal thrombosis and osteoporosis. The blood test is used to detect high levels to help diagnose infants and young adults with a family history of the problem and in individuals with medical conditions like stroke or heart attacks with no other risk factors, eye lens dislocations, mental retardation or Marfan syndrome (genetic connective tissue disorder).

Causes of homocysteine levels (high levels) are influenced by genetics and diet. For example, vitamins B 6 and B 12 help regulate homocysteine levels while stress and caffeine may raise its level. Genetics may play a role as evidenced by a rare, inherited disease (homocystinuria) where homocysteine is found elevated in the urine of infants leading to eye, bone and other abnormalities.

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Medically Reviewed on 3/21/2019

Homocysteine,Test, 6 Symptoms, Levels, and Function Symptoms

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:

  • Elevated homocysteine levels affect the interior lining of blood vessels in the body, increasing the risk of atherosclerosis or narrowing of blood vessels. This can result in early heart attack and stroke.
  • There is a relationship between the levels of homocysteine in the body and the size of the carotid arteries that supply the brain with blood; the higher homocysteine level, the narrower (stenosed) the carotid artery becomes.
  • The risk of deep vein thrombosis (DVT) and pulmonary embolism may be linked to elevated homocysteine levels.
  • There may be a relationship between elevated homocysteine levels and broken bones, especially in the elderly.
  • Alzheimer's disease and other types of dementia may be more frequently seen in patients with increased or elevated levels of the amino acid in the blood.
  • In infants who have the genetic condition homocystinuria, the inherited abnormalities affect the body's metabolism of homocysteine to cysteine. This may result in dislocation of the lens in the eye, sunken chest, Marfan-type appearance (long thin body type), mental retardation, and seizures. Neonatal strokes may also be seen with high homocysteine levels.
  • In pregnancy, homocysteine levels tend to decrease. Elevated homocysteine levels may be associated with some fetal abnormalities and with potential blood vessel problems in the placenta, causing abruption. There may also be an association with pre-eclampsia.

Homocysteine,Test, 6 Symptoms, Levels, and Function Causes

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 with a number of 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.

Anemia Symptoms and Signs, Types, Treatment and Causes Slideshow

Anemia Symptoms and Signs, Types, Treatment and Causes Slideshow

Anyone Can Have It

This illness means you have a lower than normal red blood cell (RBC) count. Normal values vary; blood tests like the complete blood count (CBC) can be explained by your doctor. Anemia may also result from low levels of hemoglobin, the protein that transports oxygen to the body. No matter what the cause, less oxygen is available and this produces weakness, dizziness, and shortness of breath. It is treatable once the underlying cause is identified. Long-standing or severe lack of oxygen can damage of the brain, heart, and other organs.


The three main causes of the illness are inadequate or faulty production of red blood cells, a high rate of destruction of red blood cells, and excessive bleeding. Megaloblastic is one type of faulty red cell production. The condition of anemia may be mild and easily treatable or severe and require immediate intervention.


Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.