Home test kit for underactive thyroid (hypothyroidism). Pack containing a kit to test for high levels of thyroid stimulating hormone (TSH) in the blood. TSH is a peptide hormone that is synthesized in the anterior pituitary gland of the brain. It stimulates the thyroid gland to secrete the hormones thyroxine and tri-iodothyronine. Thyroid hormones regulate the body's metabolism. Levels of TSH above normal indicate hypothyroidism, symptoms of which may include tiredness, feeling cold, weight gain, depression, and poor memory and concentration. Hypothyroidism is treated with thyroxine.