Homocysteine and MTHFR polymorphism testing in suspected thrombophilia

Mark Crowther, MD, MSc, is a professor of medicine, chair of the Department of Medicine, and Leo Pharma Chair in Thromboembolism Research at McMaster University.

Should homocysteine and MTHFR polymorphism testing be performed in patients with suspected thrombophilia?

MTHFR testing is never indicated. We’ve actually removed it from our test menu. There’s absolutely no clinical circumstance within which it should be performed.

Homocysteine is evaluated very frequently and is of questionable significance in the large majority of patients, but it does have a very specific role in selected patients who may have true congenital hyperhomocysteinemia, that is, in patients who have levels that are well above the upper limit of normal. This is a very rare condition and should be suspected, for example, if there’s parental consanguinity or if the person presents with very unusual thrombotic complications. But in general, it’s certainly not a first- or even second-line test that we do on our evaluation of thrombophilia.