The thyroid gland is an organ in the neck that produces hormones which are then secreted into the blood to be delivered around the body. The hormones are triiodothyronine (T3) and thyroxine (T4) and they affect how most of the cells that make up the body function. They control the body’s metabolism or the speed at which it works and their levels can be measured with a blood test.
The gland is found quite low in the neck and can be described as butterfly-shaped although each wing is more plum-shaped. The body (or isthmus) lies on the front of the windpipe and the wings wrap around the windpipe on either side. The thyroid begins life at the back of the tongue and migrates down into the neck as we develop before birth. This means that occasionally our thyroid can be found in the back of the tongue or in a swelling down the front of the neck.
The thyroid gland can go wrong functionally by becoming over or under active or structurally where it can increase in size (called a goitre) or become nodular. The two are not necessarily related in that you can have a normal-looking gland which is over or under-active or a very large or nodular gland which functions normally. Nodules or lumps in the thyroid are very common and may be present in about half of the population. The vast majority of thyroid lumps are benign however a small proportion will be cancerous so it is important to investigate any thyroid swellings.
With most benign or cancerous thyroid swellings the function of the thyroid will be normal so any blood tests will be normal. Occasionally you can get an overactive nodule which will cause the level of thyroid hormones in the blood to rise.
The main investigation of a thyroid swelling is an ultrasound scan. This will show the size of the gland, if there is one nodule or more, if the nodule is solid or cystic (fluid-filled), if there are any features to suggest that it is cancerous and if there are any associated enlarged neck glands (lymph nodes). If there is any doubt as to whether a thyroid nodule is cancerous then a needle test will be taken to remove some of the cells for analysis under the microscope.
Other tests may be undertaken for example a CT scan if there is suspicion that an enlarged thyroid is extending down into the chest, an MRI scan if there is suspicion that it it is growing into the windpipe or a nuclear medicine scan if the gland is overactive.
If a thyroid lump is found to be benign and is not causing any symptoms then it may require no treatment at all. Some benign lumps can cause symptoms if they are large enough. They may cause a feeling of pressure, or cause difficulty in swallowing in which case surgical removal will be considered. If the diagnosis is unclear following the needle test then the half of the gland containing the nodule may be removed to establish a firm diagnosis. If the lump is cancerous then the mainstay of treatment is surgery with either removal of half or all of the gland. This may be followed by treatment with radioactive iodine. Thyroid surgery may also be recommended for an overactive gland which may not be nodular.
Surgery usually involves removing half of the thyroid gland (hemithyroidectomy or thyroid lobectomy) or the whole gland (total thyroidectomy). Subtotal thyroidectomies where a small part of the gland is left used to be popular particularly when treating an overactive gland but this is rarely performed now.
The surgery is performed under a general anaesthetic and usually involves an overnight stay although in selected cases it may be possible to perform removal of half of the gland as a daycase. As with all surgery there are risks involved but the chance of a complication is very low. The main risks for either type of surgery are bleeding, infection, voice change and underactivity of the gland if half of it is removed. In addition if the whole gland is removed there is a risk of low calcium levels in the blood which may require replacement either temporarily or for life and a very low risk of problems with breathing.
Mr. Fish will be able to tell you about all of these risks on more detail including his own complication rates. Thyroid surgeons in the UK are obliged to enter their outcomes form thyroid surgery into a national audit run by the British Association of Endocrine and Thyroid Surgeons (BAETS) the results of which are published annually.
Normally it takes 2-3 weeks to recover from thyroid surgery. There are both the physical aspects of it such as wound healing and the hormonal aspects. If half of the gland is removed then in the majority of cases the remaining half of the gland can work harder to produce extra thyroid hormones. This may take some weeks to happen and so you may feel overly tired and lethargic during that period. In some cases the thyroid does not have that reserve capacity and so you need to be on thyroid hormone replacement for life (a tablet a day). Usually a blood test is taken after 4-6 weeks to see whether supplementation is required. In the long term once you are on the correct dose of thyroxine there should be no ongoing symptoms such as tiredness or weight gain and the levels need only be checked annually.