title: Metabolic clearance and production rates of human thyrotropin.
abstract: Metabolic clearance (MCR) and production rates (PR) of human thyrotropin (hTSH) were determined by the constant infusion to equilibrium method 57 times in 55 patients. 16 control patients had a mean hTSH MCR of 50.7 ml/min. The mean hTSH MCR was significantly (P < 0.02) higher in 19 euthyroid men (51.6 ml/min) than in 12 euthyroid women (43.0 ml/min), but this apparent sex difference disappeared when the MCR were corrected for surface area, 25.8 (men) versus 25.2 ml/min per m(2) (women). Hypothyroid patients had significantly (P < 0.005) lower hTSH MCR (30.9 ml/min), and hyperthyroid patients had significantly (P < 0.05) higher hTSH MCR (60.9 ml/min) than controls. The hTSH MCR in patients with "decreased thyroid reserve" (40.9 ml/min), hyperfunctioning thyroid nodule (53.8 ml/min), and "empty sella syndrome" (46.6 ml/min) were not significantly different from controls. The mean hTSH PR in controls (104.3 mU/day) was significantly (P < 0.005) different from that in patients with "decreased thyroid reserve" (956 mU/day), hypothyroidism (4,440 mU/day), hyperthyroidism (< 43.9 mU/day) and a hyperfunctioning thyroid nodule (< 38.7 mU/day). In primary hypothyroidism intravenous triiodothyronine therapy (50 mug/day) for 10 days decreased the hTSH PR (from 4,244 to 2,461 mU/day) before changes in the hTSH MCR (from 33.1 to 33.7 mU/day) were observed. These studies have demonstrated that changes in the serum concentration of hTSH are mainly due to altered pituitary hTSH secretion with only a minor contribution from the change in hTSH MCR.
mesh_terms: D000328:Adult; D000368:Aged; D000013:Congenital Abnormalities / Q000378:metabolism; D005260:Female; D006044:Goiter, Nodular / Q000378:metabolism; D006801:Humans; D006980:Hyperthyroidism / Q000378:metabolism; D007037:Hypothyroidism / Q000378:metabolism; D007275:Injections, Intravenous; D007457:Iodine Radioisotopes; D008297:Male; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D010902:Pituitary Gland / Q000378:metabolism; D012658:Sella Turcica / Q000002:abnormalities; D012737:Sex Factors; D013972:Thyrotropin / Q000096:biosynthesis / Q000097:blood / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000627:therapeutic use
chemical_list: D007457:Iodine Radioisotopes; D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine