It may be heart related. But when you say "red" turning
to "blue" those are colors associated with Raynauds. Do his hands ever look a waxy white
color, particularly the finger tips? Just another thing to think about. They can do a capillary test to see if he has Raynauds. Somehow they check the fingernail
s. I haven't had it done. My doctor took a look at my cold, gray feet and said I had Raynauds. You can google it for more information, see if it fits.