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.
Itching can be triggered by wool fibers or irritants, such as solvents or cosmetics. Itching can result from disorders that affect the skin, the nervous system (which senses itching), or other parts of the body (such as bile ducts or kidneys) or from drugs. Causes that affect more of the body than just the skin are called systemic causes.