The thyroid is a small gland at the base of the neck that synthesizes thyroid hormone, which is responsible for various actions in the body. The thyroid gland can be affected by diseases that can lead to the production of too much or too little of the hormone including goiter, hyperthyroidism, hypothyroidism, thyroid nodules and thyroid cancer. If you experience symptoms such as restlessness or fatigue and loss or weight gain, you may have a thyroid problem. It is often women and people over the age of 50 who are at the highest risk of thyroid disorders. The condition may also arise if you have a family history of thyroid disease. It is advisable to have your thyroid checked if you are at risk.