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.
Another possible explanation is that pain and itch engage many of the same areas of the brain. When you scratch an itch, you cause yourself enough pain to relive the itch, temporarily. Regardless, itches are best left unscratched. Find out what happens to your skin when you develop an itch.