Changes in the basal circulating pituitary (LH, FSH, GH, TSH, and PRL) and steroid (E2, E2, T, A, and DHEA) hormone levels, and in pituitary hormone release in response to sequential stimuli (arginine infusion, TRF, and LRF) were assessed before and from 6 weeks to 10 months after hypophysectomy as ablation therapy for metastatic breast cancer. Trans-sphenoidal removal was performed in 5 cases and cryophypophysectomy in the sixth. In 3 of the 6 patients, hypophysectomy was considered incomplete as evidenced by the presence of measurable amounts of circulating pituitary hormones and their release in response to stimuli. Nonetheless, all pituitary hormone levels except PRL were markedly reduced. In the other 3 patients, hypophysectomy was considered to be nearly complete as basal pituitary hormone levels (except PRL) were barely measurable and there was minimal response to stimulation. Basal PRL levels were essentially unchanged following hypophysectomy whether the procedure was considered endocrihologically complete or not. However, PRL release was absent in response to TRF or arginine stimulation in all except 2 patients in whom substantial residual pituitary function was still present. In all cases, hypophysectomy was followed by a marked reduction in circulating levels of estrogens and androgens, but small amounts remained measurable. In the present series of patients, the possible sources of measurable amounts of pituitary and steroid hormones, especially PRL, following hypophysectomy are discussed.
