Studies report that as many as 57.4% of patients with hives (urticaria) have the presence of thyroid antibodies. Thyroid panel tests include: TSH (thyroid stimulating hormone), free T3, free T4, thyroid antibodies - thyroid peroxidase antibody (TPOAb), and thyroglobulin antibody (TgAb).
"In conditions of chronic urticaria, thyroid antibodies are not only indicators of chronic inflammation, but they appear to play a role in the disease process. In most cases, improvement of urticaria with thyroxine replacement hormone suggests that chronic thyroid inflammation may initiate a hypersensitivity reaction and an underlying thyroid hormone deficiency.
However, rarely, patients with chronic urticaria have undiagnosed conditions of Graves' disease. Researchers in the UK have reported two instances in which patients with chronic urticaria and TPO antibodies responded well to the anti-thyroid drug carbimazole." - Thyroid Peroxidase Antibodies - TPO Autoantibodies and Their Significance by Elaine Moore.
"In about half of patients with chronic idiopathic hives, the explanation is that body's immune system is, in a sense, overactive. The urticaria is "autoimmune". The immune system is attacking the normal tissues of the body and causing hives as a result. We know certain urticaria sufferers have other signs of autoimmune problems. Some have autoimmune thyroid disease, vitiligo, swollen joints, or certain abnormalities in the blood (especially the ANA test).
A new treatment has recently emerged for autoimmune urticaria. This is the use of hydroxychloroquine, a drug originally used for malaria. In a clinical trial 83% improved or cleared completely when used for three months or more." - American Osteopathic College of Dermatology - Urticaria
Are u taking any other medication ? I went thru something very similar ... occasional severe hives. Went thru the 201 allergy reaction tests and am allergic to nothing. After a year finally tracked the hives down. My asthma inhaler Combivent was causing the hives. I have no problem with albuterol; it was the ipratropium bromide in Combivent causing the hives. I now stay away from any inhaler (like Spiriva) containing similar bromide components.
Also check meds you take for sulphur. I can tell a new med contains sulphur when my hands itch like crazy from hives.
I am also IGA deficient (immunoglobulin A deficient). Which explains why I seem to catch every cold and flu going around. Antibiotic supplementation fix this problem. If u or a child "always seem to be sick" u may want to be tested for this.