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.

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 vitamins 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 also occur due to a rare genetic disease called homocystinuria, where the enzymes needed for methionine metabolism are dysfunctional.

Increased levels of homocysteine in 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 Alzheimers disease.

This test is performed on a blood sample. A syringe with a fine needle attached is used to withdraw blood sample from a blood vessel in your arm generally from the inner side of the elbow area. The doctor, nurse or the phlebotomist will tie an elastic band around your arm which will help the blood vessels to swell with blood and hence 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 may feel a tiny pinprick during the procedure. Blood sample once collected is then sent to the laboratory.

There is no risk associated with the test. However, as this test involves a needle prick to withdraw the blood sample, rarely, a patient may experience increased bleeding, hematoma (blood collection under the skin) formation, bruising or infection at the site of needle prick.

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.

Certain medications like carbamazepine, methotrexate, etc. can affect the result of homocysteine test. Smoking and alcohol intake can increase homocysteine levels.

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

Homocystinuria is a genetic disease where metabolism of the essential amino acid 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 development of cardiovascular disease, deep vein thrombosis, pulmonary embolism, and stroke.

Increased homocysteine levels in blood show subtle symptoms similar to vitamin deficiency. These include: Fatigue and weakness Dizziness Appetite loss Pale colour 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