Differences in response of thyrotropin to 3,5,3'-triiodothyronine and 3,5,3'-triiodothyroacetic acid in patients with resistance to thyroid hormone.
This study investigated the response of TSH secretion to 3,5,3'-triiodothyronine (T3) and 3,5,3'-triiodothyroacetic acid (Triac) in patients with resistance to thyroid hormone, and compared the responses with those in patients with TSH-secreting pituitary adenoma and normal subjects. A short-term administration of 75 microg of T3 daily for 7 days suppressed serum TSH concentrations almost completely in normal subjects, but suppressed TSH only partially in patients with resistance to thyroid hormone and TSH-secreting pituitary adenoma. A single-dose administration of 75 microg of T3 gave similar results in regard to TSH suppressibility in these three subjects groups. In contrast, a single-dose administration of 1.4 mg of Triac remarkably suppressed serum TSH concentrations after 2 hours in not only normal subjects (-34 +/- 11% [mean +/- SD] from the basal value) but also in patients with resistance to thyroid hormone (-31 +/- 9%), and this TSH suppression continued for 4 hours. After 24 hours, this TSH suppression persisted in normal subjects (-62 +/- 12%) but was relieved in patients with resistance to thyroid hormone (-23 +/- 14%). After the Triac administration, molar ratios of alpha-subunit to TSH in serum were decreased in patients with TSH-secreting pituitary adenoma but increased in patients with resistance to thyroid hormone. Because the Triac therapy for patients with resistance to thyroid hormone suppressed pituitary-TSH secretion during the early phase of drug ingestion, this drug should be given several times within a day to obtain continuous TSH-suppressive effects.
Ueda
S
S
First Department of Internal Medicine, Osaka Medical College, Takatsuki, Japan.
Takamatsu
J
J
Fukata
S
S
Tanaka
K
K
Shimizu
N
N
Sakata
S
S
Yamaji
T
T
Kuma
K
K
Ohsawa
N
N
D000236:Adenoma / Q000175:diagnosis / Q000378:metabolism; D000293:Adolescent; D002675:Child, Preschool; D005260:Female; D005293:Ferritins / Q000097:blood; D015292:Glycoprotein Hormones, alpha Subunit / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D010911:Pituitary Neoplasms / Q000175:diagnosis / Q000378:metabolism; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism; D013961:Thyroid Gland / Q000503:physiopathology; D018382:Thyroid Hormone Resistance Syndrome / Q000175:diagnosis / Q000188:drug therapy / Q000503:physiopathology*; D013972:Thyrotropin / Q000097:blood / Q000378:metabolism*; D014284:Triiodothyronine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use*
D015292:Glycoprotein Hormones, alpha Subunit; D012738:Sex Hormone-Binding Globulin; D014284:Triiodothyronine; C010642:3,3',5-triiodothyroacetic acid; D013972:Thyrotropin; D005293:Ferritins