Homocysteine
Definition
Homocysteine is an amino acid; the body uses amino acids to build proteins. The body breaks down homocysteine with the help of B vitamins (B6, B12, and folic acid).
Purpose
Primarily assesses B vitamin sufficiency. It also helps diagnose homocystinuria, a rare inherited condition that affects how homocysteine is broken down; it can be used to assess cardiovascular risk in people with risk factors such as heart disease or hypertension/diabetes.
It may be ordered for symptoms of B vitamin deficiency such as dizziness, fatigue, headache, palpitations, or tingling in the hands and feet.
Results
High levels may point to insufficient B vitamin intake, homocystinuria, or increased cardiovascular risk. Results may also be associated with kidney disease, osteoporosis, and dementia.
Normal Values
Specific to the laboratory. Age, sex, and smoking affect results.
Risks and Limitations
A high homocysteine level does not always mean a condition that requires treatment. Because the link between homocysteine and heart disease outcomes is uncertain, routine screening is generally not recommended.
Fasting for 8 to 12 hours before the test may be required.