Besides drugs, hormone therapy also involves: a) Surgically removing organs or glands that produce certain hormones; enhancing the immune system can cause diseases by boosting immune response. b) Enhancing the immune system; surgically removing organs or glands that produce certain hormones can cause diseases by impairing immune response. c) Surgically transplanting organs or glands that produce certain hormones; enhancing the immune system can cause diseases by overstimulating immune response. d) Boosting the metabolic system; surgically removing organs or glands that produce certain hormones can cause diseases by reducing metabolic function.