Hi..., A low level of thyroxine and high level of TSH indicate an underactive thyroid. That's because your pituitary produces more TSH in an effort to stimulate your thyroid gland into producing more thyroid hormone... Standard treatment for hypothyroidism involves daily use of the synthetic thyroid hormone levothyroxine . This oral medication restores adequate hormone levels, reversing the signs and symptoms of hypothyroidism... The medication also gradually lowers cholesterol levels elevated by the disease and may reverse any weight gain.