Homocysteine (Total) in Serum or Plasma

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have a history of heart disease, stroke, or blood vessel problems, or if you have conditions like kidney disease, diabetes, or pernicious anemia. It may also be checked as part of routine screening for individuals at higher risk for vascular issues.

What to Expect Before the Test

You’ll typically have a small needle inserted into your arm to draw blood. Avoid eating or drinking anything (except water) for 10–12 hours before the test if fasting is required, though this may not apply to all homocysteine tests. Wear comfortable clothing and let your provider know if you’re on blood thinners.

What the Results Mean

Results are usually reported as a concentration in micromoles per liter (µmol/L). While reference ranges vary by lab, elevated levels may signal increased risk for cardiovascular disease or other complications. Your provider will interpret results in the context of your overall health.

Common Causes of Abnormal Results

Homocysteine levels can rise due to genetic factors, certain medications (like folic acid or vitamin B supplements), kidney disease, or conditions affecting folate or vitamin B12 metabolism. Low levels may occur with deficiencies of these vitamins.