I have been dealing with hives for over five years they come and go, lately staying around. Always when I wake up in the morning. I was told it was linked to thyroid. I had a history of sub clinical hyperthyroid and now, Have hypo thyroid. For those who suffer from hives ask to be tested for t3, t4 free the blood test will tell you if you have thyroid issues. It took a dermatologist who parallel the hives, I have read about it no doctor linked it until now. I have had allergy test nothing came about.