Why do my fingers turn blue and really cold when I'm cold?

Raynaud's. Raynaud's sometimes is called a disease, syndrome, or phenomenon. The disorder is marked by brief episodes of vasospasm (va-so-spazm), which is a narrowing of the blood vessels. Vasospasm of the arteries reduces blood flow to the fingers and toes. In people who have raynaud's, the disorder usually affects the fingers. In about 40 percent of people who have raynaud's, it affects the toes.