One person in twenty will experience a thyroid problem at some stage. For the sufferer the result can be a bewildering variety of physical and psychological symptoms, from breathlessness to flaky skin, and from weariness to irritability. Fortunately, once thyroid disease has been diagnosed, the chances of successful treatment are high. Modern approaches to management, involving drugs or occasionally surgery, allow most people with thyroid problems to overcome them completely. In clear non-technical language, Dr Toft explains the working of the thyroid, what can go wrong, and how the problems are treated.