Hi...I Have A Friend Who Is On Dialysis And She

Hi...I have a friend who is on dialysis and she is now experiencing discoloration of her fingernails most thumb and index fingers. She had some issues with blisters, but no longer have blisters. Can you tell me what might be causing this and what she should do? She went to a dermatologist, but the doctor could not figure out what was going on. Thanks Rosemary. My e-mail address is YYYY@YYYY