Raynaud's disease due to low blood flow or worsened with mild dehydration?

It is a vasospasm... Raynaud's disease causes low blood flow in periphery, e.g. Fingers, due to spasm in small peripheral arteries like in hands and feet. Accordingly, discoloration, tingling, numbness, and even pain develop. Due to the already decreased circulating blood volume in dehydration, a raynaud's condition could conceivably appear worse.