Thyroxine is produced by thyroid gland under the effect of TSH from anterior pituitary. Its deficiency/hyposecretion causes cretinism in children and myxoedema in adult. Its hypersecretion causes thyrotoxicosis. Goitre is the term used for enlarged thyroid gland irrespective of if s functional status i.e. the gland may be hyperthyroid, hypothyroid or euthyroid (normal)