An instrument for therapeutically cytotoxically ablating parathyroidal tissue is disclosed. A substance delivery device with which a quantity of an activator substance that is less than a cytotoxic ablation quantity threshold of a parathyroid gland can be percutaneously introduced into parathyroidal tissue is provided. The activator substance, when introduced, is not activated. An energy source device that includes a selector with which a quantity of an energy that is less than a cytotoxic ablation energy threshold of the parathyroid gland can be selected and an energy production device operable to apply the energy to the activator substance is provided. The activator substance, when introduced, and the energy indicated, when applied to the introduced activator substance, are in combination capable of cytotoxically ablating the parathyroid tissue and transforming the parathyroid gland from overproduction to non-overproduction of the parathyroid hormone in a manner that maintains non-parathyroidal tissue functions and is non-lethal.
