1 An adenoma is a part of the gland that has walled itself off from the rest of the gland, forming noncancerous (benign) lumps that may cause an enlargement of the thyroid. Not all adenomas produce excess T-4, and doctors aren't sure what causes some to begin producing too much hormone.  Thyroiditis.
Scratching Itchy Skin Causes Brain To Release Hormone Serotonin, Intensifies Itchy Sensation. While a good scratch may temporarily relieve you of your itch, it actually stimulates serotonin in the brain that intensifies the itchy feeling.
One of them, histamine, is responsible for the symptoms that appear on your skin. Depending on the type of reaction and its severity, the duration of symptoms can vary from days to weeks. Hives are the red, itchy bumps that show up due to a food or drug allergy. They normally go away after a few days. However, some cases of chronic hives can last for months or years. Until hives go away, you can relieve symptoms using antihistamines. Meanwhile, allergic contact dermatitis is the rash that results from you touching something you're allergic to.