Interpreting Results

Overview of Homocysteine

What is Homocysteine?

Homocysteine is an amino acid which at increased levels in the body can damage the inner lining of the blood vessels resulting in increased chances of blood clot formation. The Homocysteine Test measures the levels of homocysteine in the blood.

Why is Homocysteine done?

The Homocysteine Test is performed:

  • To screen for heart attack and stroke, especially in people with no risk factors but with a family history of cardiovascular diseases.
  • To detect and diagnose an inherited disease called homocystinuria in newborns and infants
  • To detect deficiency of Vitamin B6, B12, or Folic acid

What does Homocysteine Measure?

The Homocysteine Test measures the levels of homocysteine in the blood.

Homocysteine is an amino acid which is an intermediate in the production of cysteine from methionine. Methionine is obtained from dietary sources, mainly fish, meat, and dairy products, and is converted to homocysteine, and then to cysteine in the body. This conversion from methionine to cysteine is regulated by various enzymes which require Vitamin B6, B12, and folic acid to work. Deficiency of these vitamins causes an increase in the levels of homocysteine in the body. Increased homocysteine levels in the blood can be due to a rare genetic disease called homocystinuria, where the enzymes needed for methionine metabolism are dysfunctional.

Increased levels of homocysteine in the blood are associated with an increased risk of cardiovascular diseases including atherosclerosis, thrombosis (formation of blood clots) in blood vessels, heart attack, and stroke. It has also been implicated in some studies with an increased risk of Alzheimer’s disease.

Preparation for Homocysteine

  • Do not eat or drink anything other than water for 8-12 hours before the test.

Sample Type for Homocysteine

The sample type collected for Homocysteine is: Blood

Interpreting Homocysteine results


Normal homocysteine levels: 4 to 15 µmol/L

Concentrations above 15µmol/L are considered increased homocysteine level. Increased level of homocysteine in the blood is called Hyperhomocysteinemia, which is classified into:

·         Moderate hyperhomocysteinemia: 15 to 30 µmol/L

·         Intermediate hyperhomocysteinemia: 30 to 100 µmol/L

·         Severe hyperhomocysteinemia: More than 100 µmol/L

Hyperhomocysteinemia can be caused due to:

·         Deficiency of Vitamin B6, B12, or Folic acid

·   Inherited disease homocystinuria (Genetic abnormality of methionine metabolizing enzymes)

·         Chronic alcoholism

The normal level of homocysteine in the blood is usually higher in males than in females. Homocysteine levels also increase with age.

Answers to Patient Concerns & Frequently Asked Questions (FAQs) about Homocysteine

Frequently Asked Questions about Homocysteine

Q. How is this test performed?
This test is performed on a blood sample. A syringe with a fine needle is used to withdraw blood from a blood vessel in your arm. The healthcare provider will tie an elastic band around your arm to make the blood vessels swell with blood. This makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You will feel a tiny pinprick during the procedure. Blood sample once collected will then be sent to the laboratory.
Q. Is there any risk associated with this test?
There is no risk associated with the test. However, since this test involves a needle prick to withdraw the blood sample, in very rare cases, a patient may experience increased bleeding, hematoma formation (blood collection under the skin), bruising or infection at the site of needle prick.
Q. Is there any preparation required before the homocysteine test?
A fasting period of 10 to 12 hours is prescribed before the test. Inform the doctor of any medications you may be taking. No other specific preparations are usually required before the Homocysteine Test.
Q. What factors can affect the homocysteine test results?
Certain medications like carbamazepine, methotrexate, etc. can affect the result of homocysteine test. Smoking and alcohol intake can increase homocysteine levels.
Q. What additional tests can be prescribed by your doctor in case homocysteine test result is not normal?
Additional tests that may be prescribed in case of abnormal homocysteine test result are: · Urine Homocysteine Test · Lipid Profile Test · Cardiovascular Disease Screening Tests · Vitamin B12 Test · Folic Acid Test
Q. What is Homocystinuria?
Q. What is Homocystinuria? Homocystinuria is a genetic disease where metabolism of an essential amino acid called methionine is affected, leading to increased levels of homocysteine in blood. Homocystinuria is caused due to an inheritable genetic mutation which causes abnormalities in the enzymes required for methionine metabolism. Symptoms of homocystinuria appear in infants within a few years of birth. Symptoms include dislocation of the eye lens leading to visual defects, muscular and skeletal deformities, osteoporosis, long and slender body structure (Marfan syndrome like appearance), seizures, mental retardation, etc. Infants affected by homocystinuria are also at a higher risk of developing cardiovascular diseases, deep vein thrombosis, pulmonary embolism, and stroke.
Q. What are the symptoms of increased homocysteine levels?
Increased homocysteine levels in blood show subtle symptoms similar to vitamin deficiency. These include: · Fatigue and weakness · Dizziness · Appetite loss · Pale color · Reduced blood pressure · Increased heart rate · Shortness of breath · Soreness in mouth · Visual defects · Osteoporosis · Increased risk of cardiovascular diseases like heart attack and stroke · Increased risk of blood clot formation inside blood vessels
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