Lack of TSH inhibition by exogenous L-T4 in a patient with follicular thyroid carcinoma.
We report a case of a male patient thyroidectomized for follicular thyroid carcinoma and presenting extremely elevated serum thyrotropin levels under L-T4 suppressive therapy. Administration of L-T3 in increasing amounts resulted in a significant decrease of serum TSH levels. The nature of the possible molecular defects underlying this unusual condition and pitfalls arising from the failure of L-T4 therapy to inhibit TSH secretion in a patient in post-surgical follow-up for follicular carcinoma are discussed.
Bruno
R
R
Endocrinology Unit, Tinchi Hospital, Matera, Italy. roccobruno1@virgilio.it
Giannasio
P
P
Bellitti
P
P
Sinisi
R
R
Arturi
F
F
Russo
D
D
Costante
G
G
D018263:Adenocarcinoma, Follicular / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013964:Thyroid Neoplasms / Q000378:metabolism*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine