Thyroid hormone therapy modulates hypothalamo-pituitary-adrenal axis.
To observe the influence of thyroid hormone therapy on hypothalamo-pituitary-adrenal (HPA) axis, a group of 14 athyreotic women due to thyroid cancer treatment were studied before and after thyroid suppression therapy with thyroxine (T4). Changes in plasma adrenocorticotropin (ACTH) and cortisol levels in response to human corticotropin-releasing hormone (hCRH; 100µg, i.v.) were estimated under hypothyroid conditions and after T4 suppression therapy with 2.5µg/kg/day for two months (n=14). A group of seven healthy women was evaluated as a control group. A greater increase in ACTH levels by hCRH was observed in patient group both before and after suppression therapy compared than that of control group. Plasma cortisol levels after hCRH stimulation were also greater in patient group both before and after suppression therapy than that of control group. In conclusion, both hypothyroidism and subclinical hyperthyroidism with suppressive doses of thyroid hormone induced a hypersensitivity of ACTH to hCRH. Considering the role of thyroid hormone on HPA axis, the mechanisms of ACTH hypersensitivity may be different between these two conditions.
Center of Biomedical Research La Sabana University, Chia, Colombia. fernando.lizcano@unisabana.edu.co
Fernando
F
Lizcano
Javier Salvador
JS
Rodríguez
D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D003346:Corticotropin-Releasing Hormone; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D006980:Hyperthyroidism / Q000139:chemically induced / Q000503:physiopathology; D007030:Hypothalamo-Hypophyseal System / Q000187:drug effects* / Q000502:physiology; D007037:Hypothyroidism / Q000188:drug therapy / Q000209:etiology / Q000503:physiopathology; D007457:Iodine Radioisotopes / Q000627:therapeutic use; D008875:Middle Aged; D010913:Pituitary-Adrenal System / Q000187:drug effects* / Q000502:physiology; D013964:Thyroid Neoplasms / Q000188:drug therapy / Q000532:radiotherapy / Q000601:surgery; D013965:Thyroidectomy; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000009:adverse effects* / Q000627:therapeutic use
D007457:Iodine Radioisotopes; D000324:Adrenocorticotropic Hormone; D013972:Thyrotropin; D003346:Corticotropin-Releasing Hormone; D013974:Thyroxine; D006854:Hydrocortisone