"When do Raynaud symptoms merit a workup for autoimmune rheumatic disease?"
Cleve Clin JM Jan 2013 
http://ccjm.org/content/80/1/22
"CLUES TO PRIMARY VS SECONDARY RAYNAUD PHENOMENON
A diagnostic algorithm of digital ischemia (FIGURE 2) illustrates the range of presentations and possible causes. In Raynaud phenomenon, cold temperature and emotional stress provoke reversible color changes of the fingers and toes. Intense vasospasm of the digital arteries produces three well-defined phases1: white (pallor resulting from vasospasm), blue (dusky cyanosis due to deoxygenation of static venous blood) (FIGURE 1), and red (reactive hyperemia after the restoration of blood flow). However, only about 60% of patients have all three color changes. The attacks are associated with paresthesias, an uncomfortable feeling of coldness in the fingers, and ischemic pain. . . "