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.
Exposure to poison ivy, oak, or sumac causes an itching skin rash that usually appears within 24-72 hours. The rash usually starts as small red bumps and later develops blisters of variable size. The rash may crust or ooze. It may look like red, bumpy lines or streaks on the skin.