These disorders include hypothyroidism and hyperthyroidism. Hypothyroidism is a disorder in which an underactive thyroid is diagnosed. Women over the age of sixty are more likely to develop an underactive thyroid than other individuals. If left untreated, it can potentially lead to obesity, joint pain, heart disease and other health complications. In contrast, hyperthyroidism is a disorder in which a person is diagnosed with an overactive thyroid. This can cause nervousness and anxiety, hyperactivity, unexplained weight loss, and swelling of the thyroid gland causing a large lump to form on the throat (known as bloat).).