Blood Clotting Disorder Hypercoagulation Hyperhomocysteinemia

Hyperhomocysteinemia is a blood disorder marked by an excess amount of the amino acid homocysteine in the blood stream. While healthy levels of homocysteine in the blood are thought to help regulate metabolism and insulin absorption, high levels of this amino acid significantly strain the heart and damage the bones.

Homocysteine levels are measured with a fasting blood test (a test where the patient does not eat or drink for a period of time before the test). Here is how doctors read the levels of homocysteine in the blood to determine whether or not a patient suffers from hyperhomocysteinemia:

Test results Diagnosis
5 to 15 mmol/L Normal levels
15 to 30 mmol/L Moderate hyperhomocysteinemia
30 to 100 mmol/L Intermediate hyperhomocysteinemia
Over 100 mmol/L Severe hyperhomocysteinemia

While severe hyperhomocysteinemia is a rare condition, 5 percent to 7 percent of the population lives with mild hyperhomocysteinemia. In general, the older people get, the higher levels of homocysteine they will have in their blood.

Hyperhomocysteinemia Causes and Risk Factors

Some of the known causes of hyperhomocysteinemia include:

  • genetic mutations: Recent studies have determined that mutations on the MTHFR gene may be responsible for moderate cases of hyperhomocysteinemia.
  • medications: Some people acquire hyperhomocysteinemia by taking certain medications, including anticonvulsants, cyclosporine, methotrexate and theophylline.
  • nutritional deficiencies: Up to two-thirds of all hyperhomocysteinemia cases are due to nutritional deficiencies. These deficiencies make it difficult to metabolize folate, B12 and B6, all vitamins that in turn help control levels of homocysteine.
  • other medical conditions: The presence of other, more serious underlying disorders can cause hyperhomocysteinemia. Liver disease, kidney disease, hypothyroidism and some cancers can all increase homocysteine to dangerous levels.
  • rare metabolic disorders: When a person’s metabolism isn’t fast enough to process the homocysteine in the blood, levels of this amino acid increase to unhealthy levels, causing hyperhomocysteinemia.

Hyperhomocysteinemia Symptoms

Early detection of hyperhomocysteinemia is complicated by a lack of visible symptoms. In fact, a person with mild hyperhomocysteinemia may have no visible symptoms until well into their 30s or 40s. However, when symptoms are present, patients experience:

  • general pain and achiness
  • heart disease
  • inflammation
  • recurring blood clots
  • vascular damage.

Unfortunately, if symptoms are present, the case of hyperhomocysteinemia has likely progressed to a serious health risk.

Diagnosing Hyperhomocysteinemia

In general, doctors diagnose hyperhomocysteinemia when performing blood work to check homocysteine levels when treating the following conditions:

  • heart attack
  • heart or kidney transplants
  • high levels of homocysteine in urine
  • kidney failure
  • peripheral vascular disease
  • premature arteriovascular disease
  • recurring pulmonary embolism
  • stroke
  • venous thrombosis.

The standard blood test for diagnosing hyperhomocysteinemia is a fasting blood test, a blood test that measures a patient’s blood factors (including the concentration of homocysteine) after he hasn’t eaten in at least eight hours.

Hyperhomocysteinemia treatment

Hyperhomocysteinemia treatment usually revolves around making the necessary dietary changes to keep homocysteine levels at healthy levels. Doctors recommend that patients consume more or take supplements of folic acid (found in dark, leafy greens), B6 and B12 vitamins.

Researchers are still exploring whether or not reducing homocysteine to normal levels alters hyperhomocysteinemia’s effect on heart disease. Further study is needed to confirm or reject this suspicion.

While treating hyperhomocysteinemia, health complications caused by high homocysteine levels also need to be addressed. For example, if the hyperhomocysteinemia has caused a pulmonary embolism, then both conditions will need to be treated. As with most conditions, the earlier hyperhomocysteinemia is detected, the more effective treatment tends to be.

Complications of Hyperhomocysteinemia

If left untreated, hyperhomocysteinemia causes:

  • atherosclerosis, a constriction of the arteries that limits blood flow to the heart
  • coronary disease
  • heart attacks (A person with homocysteine levels greater than 15 mml/L have experience heart attacks with twice the frequency found in the general population.)
  • miscarriages
  • pulmonary embolism, blood clot obstruction in the lungs
  • retinal thrombosis, blood clots in the retina
  • vascular damage
  • venous thrombosis, or blood clots (People who develop recurring blood clots are 1.8 times more likely to have hyperhomocysteinemia than the rest of the population.).


Cortese, A. (2003). Hyperhomocysteinemia. Retrieved September 21, 2007, from the transfusion Medicine Update Web site:

Health Alliance (2004). Hyperhomocysteinemia: An Inherited or acquired Independent Risk Factor for Atherothrombotic Vascular Disease. Retrieved September 21, 2007, from the Health Alliance Web site: