RP is due to changes in the flow of blood to the fingertips. When the finger is white or pale, there is very little blood in the finger. When the fingertip is blue, there is blood present but the flow is so slow that the oxygen has left the blood, turning the blood blue rather than red.
Classification and causes
When there is no evidence of an underlying illness, this condition is termed "primary" RP. RP can, however, be an early symptom of an underlying disease and, in those cases, is "secondary" RP. Any condition that slows blood flow to the fingertips may cause RP.
Illnesses associated with RP include atherosclerosis ("artery hardening"), abnormal proteins in the blood, a blood vessel disease caused by smoking (Buerger's disease), inflammation in the blood vessels (vasculitis) and by several autoimmune connective tissue diseases.
The connective tissue diseases most likely to cause RP are scleroderma, dermatomyositis, and systemic lupus erythematosus. Rheumatoid arthritis can sometimes cause RP. RP is a nearly universal symptom of scleroderma (occurs in up to 90% of the patients) and is the most common first symptom. Several decades may pass from the time of onset of RP until the diagnosis of scleroderma is made. In other cases, the nature of the scleroderma is evident shortly after, or even before, the onset of the RP.
Clinical picture (symptoms and signs)
Most often Raynaud's phenomenon affects the fingers and toes. It can also affect the ears and nose. One's fingertips turning blue or white upon exposure to cold. The color returns to normal on warming. The cold exposure can be in any of several forms, including cool ambient temperatures, picking up a cool object or drinking a cool drink. Sometimes people who experience RP notice that the fingertip turns red after the blue or white period. RP episodes may last minutes to hours, but are most often about 10 to 15 minutes long. People frequently have episodes associated with driving in cold weather, opening the food freezer, drinking cold drinks, and entering air-conditioned areas.
RP is a common trait among perfectly healthy people. Between 5 and 10% of healthy people have RP.