The Journal of clinical endocrinology and metabolism
-
J. Clin. Endocrinol. Metab. · Jul 1999
Phytoestrogens alter adrenocortical function: genistein and daidzein suppress glucocorticoid and stimulate androgen production by cultured adrenal cortical cells.
Phytoestrogens influence a variety of biological processes. As 17beta-estradiol alters adrenocortical cell function, we examined whether the dietary phytoestrogens, genistein and daidzein, have related effects. In cultured human fetal and postnatal adrenal cortical cells, genistein and daidzein (both 0.4-40 micromol/L) decreased ACTH-stimulated cortisol production to basal levels (ED50, 1-4 micromol/L). ⋯ However, genistein and daidzein specifically inhibited the activity of 21-hydroxylase (P450c21); the activities of other steroidogenic enzymes were not affected. Thus, phytoestrogens may decrease cortisol synthesis by suppressing the activity of P450c21 and, as a consequence, increase DHEA/DHEA-S synthesis by shunting metabolites away from the glucocorticoid synthetic pathway. Therefore, consumption of foods containing phytoestrogens may alter adrenocortical function by decreasing cortisol and increasing androgen production.
-
J. Clin. Endocrinol. Metab. · Jul 1999
Comparative Study[18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography localizes residual thyroid cancer in patients with negative diagnostic (131)I whole body scans and elevated serum thyroglobulin levels.
Progressive dedifferentiation of thyroid cancer cells leads to a loss of iodine-concentrating ability, with resultant false negative, whole body radioactive iodine scans in approximately 20% of all differentiated metastatic thyroid cancer lesions. We tested the hypothesis that all metastatic thyroid cancer lesions that did not concentrate iodine, but did produce thyroglobulin (Tg), could be localized by [18F]2-fluoro-2-deoxy-D-glucose (FDG)-positron emission tomography (PET). We performed FDG-PET on 37 patients with differentiated thyroid cancer after surgery and radioiodine ablation who had negative diagnostic 131I whole body scans during routine follow-up. ⋯ No FDG-PET scans were positive in stage I patients; however, they were always positive in stage IV patients with elevated Tg levels. An elevated TSH level (i.e. hypothyroidism) did not increase the ability to detect lesions. FDG-PET is able to localize residual thyroid cancer lesions in patients who have negative diagnostic 131I whole body scans and elevated Tg levels, although it was not sensitive enough to detect minimal residual disease in cervical nodes.