Why do I need a homocysteine test?
You may need this test if you have symptoms of a vitamin B or folic acid deficiency. These include:  
Dizziness
Weakness
Fatigue
Pale skin
Sore tongue and mouth
Tingling in the hands, feet, arms, and/or legs (in vitamin B12 deficiency)
You may also need this test if you are at high risk for heart disease because of prior heart problems or a family history of heart disease. Excess levels of homocysteine can build up in the arteries, which may increase your risk of blood clots, heart attack, and stroke.
