Hyperthyroidism is a condition where the thyroid gland becomes overactive and produces too much of the thyroid hormones (tetraiodothyronine (T4) and triiodothyronine (T3)). The thyroid is in the neck, located in front of the windpipe (trachea), and produces hormones that regulate heart rate and body temperature. Symptoms of hyperthyroidism include nervousness, anxiety and irritability, mood swings difficulty sleeping, persistent tiredness and weakness, difficulty sleeping, sensitivity to heat, swelling in the neck from an enlarged thyroid gland (goitre), irregular and/or unusually fast heart rate (palpitations), twitching or trembling, and weight loss. Hyperthyroidism can occur due to a number of reasons: Graves' disease – an autoimmune condition where the immune system mistakenly attacks and damages the thyroid; overactive thyroid nodules (lumps) on the thyroid which can produce thyroid hormones, causing elevated thyroid levels; medicines such as amiodarone, which is used to treat an irregular heartbeat (arrhythmia); excessive iodine consumption through dietary supplements or medication – iodine can over-stimulate the thyroid; increased thyroid hormone medicine intake – occurs in patients taking with thyroid hormones to correct hypothyroidism (underactive thyroid gland); Thyroiditis – an inflamed thyroid, which can be subacute (painful, enlarged thyroid, possibly from a virus or bacteria), postpartum, and silent (painless, possibly enlarged thyroid). Risk factors for hyperthyroidism include genetics, pernicious anemia (a vitamin B12 deficiency), type 1 diabetes, primary adrenal insufficiency, and aged over 60 years. The methods for diagnosis include a cholesterol test – low cholesterol is an indication of elevated metabolic rate; tests to measure how much thyroid hormone (T4 and T3) is in the blood; thyroid stimulating hormone (TSH) test – a hormone that stimulates the thyroid gland to produce hormones. When thyroid hormone levels are normal or high, TSH should be lower. An abnormally low TSH is indicative of hyperthyroidism; triglyceride test – a sign of elevated metabolic rate; ultrasound, CT, or MRI scans to examine size of the thyroid and presence of any tumors. Treatments options are (1) Antithyroid Drugs e.g. methimazole and propylthiouracil (PTU) which prevent the thyroid gland from making new thyroid hormones, (2) Radioiodine treatment – radiotherapy to destroy cells in the thyroid, reducing its ability to produce thyroid hormones, (3) Surgery to remove some or all of the thyroid to permanently stop hormone production. An endocrinologist is the specialist who treats this condition.