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 is a common symptom. In the case of an allergic dermatitis, itching can be severe. You may have red, streaky, or patchy rash where the substance touched the skin. The allergic reaction is often delayed so that the rash may not appear until 24 to 48 hours after exposure.