What causes thyroid problems?

Thyroxin is given to people with an under-active thyroid that can't make enough thyroxin by themselves. People with low levels of thyroxin in their blood often have a slower heart rate, have a tendency to put on weight, and feel lethargic. Interestingly, only one in five of all cases of thyroid under-activity will be in men. Doctors tailor the amount of thyroxin given to patients to ensure that the patient's body is working at the right level. Without knowing exactly what is wrong with your thyroid, it is hard to say what caused it to become under-active. Sometimes its caused by insufficient iodine in the diet. Historically underactive thyroids were common in Derbyshire causing people to develop a neck 'goitre' (swollen thyroid) - termed 'Derbyshire neck' - because their diets were deficient in iodine. However, most cases are caused by an autoimmune response, whereby the body starts attacking its own tissues. The reasons for thyroid problems can therefore be partly genetic, and partly environmental.