TEL-AVIV, ISRAEL. Raynaud's phenomenon (RP) involves a disruption of blood flow to
fingers or toes resulting in cold, numbness, and a characteristic white colour of the
affected parts. RP is often associated with scleroderma or systemic lupus erythematosus
(secondary RP), but can also occur as a separate disease entity (primary RP or
Raynaud's disease). The cause of the phenomenon is unknown, but it is believed that an
abnormality in the endothelium (the single layer of cells that line the blood vessels) is
involved.
Now researchers at Tel-Aviv University report that high blood plasma levels of
homocysteine are closely associated with RP. Their study involved 10 patients with
primary RP, 10 patients with RP secondary to scleroderma, and 20 healthy controls. The
researchers measured plasma levels of homocysteine and folate (folic acid) in fasting
blood samples taken from all participants. They found the average (mean) homocysteine
level of controls to be 5.9 micromol/L; patients with primary RP had a mean homocysteine
level of 15.5 micromol/L while patients with secondary RP had a mean level of 11.6
micromol/L. A level above 10.5 micromol/L is considered excessive and is associated
with an increased risk for heart disease and stroke. Homocysteine levels tend to be
inversely proportional to folate levels. In this study controls had a mean folate level of
8.84 nanograms/mL, patients with primary RP had a mean level of only 4.79 ng/mL while
patients with secondary RP had a mean level of 7.15 ng/mL.
The researchers speculate that high homocysteine levels may be, at least in part,
responsible for the abnormal behaviour of the endothelium in RP patients. They suggest
further work to investigate this connection and, if indeed proven, recommend that RP
patients be treated with folic acid supplementation.
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