Raynaud's disease refers to a disorder in which the fingers or toes (digits) suddenly experience decreased blood circulation.

Raynaud's disease can be classified as one of two types: primary (or idiopathic) and secondary (also called Raynaud's phenomenon).

Primary and idiopathic are words used to describe a condition which occurs by itself, with no other accompanying conditions that could be considered the cause. Primary Raynaud's disease is more mild, and causes fewer complications. About half of all cases of Raynaud's disease are of this type. Women are five times more likely than men to develop primary Raynaud's disease, and the average age of diagnosis is between 20 and 40 years. About 30% of all cases of primary Raynaud's disease progress after diagnosis, while 15% of cases actually improve.

Secondary Raynaud's disease is more complicated, severe, and more likely to progress. A number of medical conditions predispose a person to secondary Raynaud's...