A healthy thyroid produces several hormones such as T3, T4 and calcitonin. In the body, T4 is converted to the active hormone T3, which stimulates metabolism.
An imbalance in thyroid hormones can occur when the thyroid gland produces too little thyroid hormone (hypothyroidism) or an excessive thyroid hormone (hyperthyroidism). Both of these conditions can lead to various symptoms and may increase your risk for cardiovascular disorders, obesity, and osteoporosis.