Hypothyroidism is an underactive thyroid gland. Hypothyroidism means that the thyroid gland can’t make enough thyroid hormone to keep the body running normally. Among the drugs affecting the thyroid gland, no drug has puzzled, and at the same time fascinated, endocrinologists more than amiodarone. Amiodarone is a potent class III anti-arrhythmic drug that also possesses beta-blocking properties. The British Thyroid Foundation is a UK charity dedicated to supporting people with thyroid disorders and helping their families and people around them to understand the condition. Indications for Thyroid Function Testing Screening for Thyroid Dysfunction Which Thyroid Function Test? As a baseline screening test TSH sampling will be done on all samples received for The thyroid gland, or simply the thyroid, is an endocrine gland in the neck, consisting of two lobes connected by an isthmus. It is found at the front of the neck, below the Adam's apple. Thyroid function tests (TFTs) is a collective term for blood tests used to check the function of the thyroid. TFTs may be requested if a patient is thought to suffer from hyperthyroidism (overactive thyroid) or hypothyroidism (underactive thyroid), or to monitor the effectiveness of either thyroid-suppression or hormone replacement therapy. Amiodarone is a potent antiarrhythmic drug that is used to treat ventricular and supraventricular tachyarrhythmias. It is a benzofuran-derived, iodine-rich compound with some structural similarity to thyroxine (T4). Interference with TFT interpretation due to committant drug therapy. Amiodarone interferes both with the synthesis of TSH, with iodine uptake by the thyroid gland and with conversion of T4 to T3. Discussion. TSH is the most sensitive test for primary hypothyroidism; A decreased T3 and T4 causes an increase in TSH, and an increase in T3 and T4 causes a decrease, with normal thyroid and anterior pituitary/hypothalamus function Click here for Frequently Asked Questions on Amiodarone. Amiodarone is a medication commonly used to treat patients with irregular heart beats, or cardiac arrhythmias.