Test Overview

A homocysteine test measures the amount of the amino acid homocysteine in the blood.

Why It Is Done

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.

How To Prepare

In general, you don't need to prepare before having this test. Your doctor may give you some specific instructions.

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

How It Is Done

A health professional uses a needle to take a blood sample, usually from an arm.

How It Feels

You may feel nothing at all from the needle, or you may feel a quick sting or pinch.

Risks

There is very little chance of having a problem from this test. A small bruise may form at the site.

Results

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 or kidney disease.