Homocysteine blood test

A homocysteine blood test is done to:

• Help identify vitamin B12 deficiency or folate deficiency. But other tests for these deficiencies are available.
• Help identify a rare inherited disease (homocystinuria) that causes a deficiency of one of several enzymes needed to convert food to energy.
• Help determine a cause for otherwise unexplained blood clots.

The health professional drawing your blood will:

• Wrap an elastic band around your upper arm to stop the flow of blood. This makes the veins below the band larger so it is easier to put a needle into the vein.
• Clean the needle site with alcohol.
• Put the needle into the vein. More than one needle stick may be needed.
• Attach a tube to the needle to fill it with blood.
• Remove the band from your arm when enough blood is collected.
• Put a gauze pad or cotton ball over the needle site as the needle is removed.
• Put pressure on the site and then put on a bandage.

Do not eat or drink anything (other than water) for at least 8 hours before the test.

Many medicines may affect the results of this test. Be sure to tell your doctor about all the nonprescription and prescription medicines you take.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results will mean.

Results are ready in 24 hours.

Normal

Each lab has a different range for what’s normal. Your lab report should show the range that your lab uses for each test. The normal range is just a guide. Your doctor will also look at your results based on your age, health, and other factors. A value that isn’t in the normal range may still be normal for you.

High values

High values of homocysteine may be caused by:

• Not getting enough folic acid, vitamin B6, or vitamin B12 in your diet.
• Other conditions or diseases, such as homocystinuria, kidney disease, hypothyroidism, Alzheimer's disease, or certain cancers.
• Using too much alcohol.
• Your sex. Homocysteine levels are normally higher in men than in women.
• Age. Homocysteine levels get higher as you get older.

Low values

Low values of homocysteine may be caused by some medicines or vitamins such as daily folic acid, vitamin B12, or niacin.