The thyroid gland is located in the lower part of the neck, below the Adam’s apple, wrapped around the trachea (windpipe). It produces hormones which help regulate the heart rate, blood pressure, body temperature and metabolism (the rate at which food is converted into energy). Thyroid disorders can include an overactive gland, called hyperthyroidism, or an underactive gland, called hypothyroidism. Both can result in an enlarged thyroid gland. Sometimes surgery is required to remove the thyroid gland. A thyroid nodule is a small swelling or lump in the thyroid gland. They are usually examined with imaging such as ultrasound or MRI, and a fine-needle aspiration biopsy, a relatively painless procedure to take tissue fluid samples from the nodule. Thyroid surgery may be required when: the biopsy indicates the nodule is cancerous; the nodules are getting bigger; or the trachea or oesophagus is compressed because the thyroid is very large. Thyroid surgery involves removing part or all of the thyroid gland, under general anaesthesia. Usually, the lobe of the thyroid gland containing the nodule lump is removed. An analysis of tissue will determine if the rest of the thyroid gland should be removed, during the same surgery. (Alternatively, surgery may be done at a later date.) The patient may be required to undergo thyroid replacement treatment if the gland is removed.