The condition of having an underactive thyroid is called hypothyroidism. This is a state of thyroid hormone deficiency or lack of thyroid hormones. It may be caused by an abnormality in the thyroid gland itself which is called primary hypothyroidism or by an insufficient level of thyroid stimulating hormone (TSH) causing under stimulation of the thyroid gland resulting to low thyroid hormone production. Underactive Thyroid Symptoms Signs and symptoms of thyroid hormone deficiency reflect the need for thyroid hormones in metabolism and its effect on all organs. Patients present with thickened features and puffy appearance. Swelling around the eyes and » » » [Read more]