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.
Medications can cause itching of the skin indirectly from drying of the skin or directly by causing an allergic reaction. Water pills, also called diuretics, used to treat high blood pressure or swelling of the extremities can lead to dry skin and itching particularly in the winter.