Which therapy is typically used as a replacement for underactive thyroid?

Hormone therapy is specifically used to address conditions related to hormone deficiencies, including an underactive thyroid, also known as hypothyroidism. In this case, the therapy typically administered is levothyroxine, a synthetic form of the thyroid hormone thyroxine (T4). This therapy helps to restore normal hormone levels in the body, which is essential for metabolism and overall bodily functions.

In contrast, chemotherapy is primarily utilized for cancer treatment, aiming to kill or slow the growth of cancer cells rather than to correct hormonal imbalances. Palliative therapy focuses on relieving symptoms and improving quality of life for patients with serious illnesses without necessarily treating the underlying condition. Immunotherapy works by enhancing the body's immune response to fight against specific diseases, particularly cancers, rather than addressing hormone deficiency disorders. Thus, hormone therapy is the most appropriate choice for replacing an underactive thyroid.