Highly sensitive determination of TSH in the follow-up of TSH-suppressive therapy of patients with differentiated thyroid cancer.
Basal and TRH-stimulated TSH levels were determined in 72 patients with differentiated thyroid cancer on hormonal treatment, using a highly sensitive immunoradiometric assay (IRMAclon, Henning). 43 patients were under treatment with levothyroxine (T4), 29 patients with triiodothyronine (T3). In 33/43 patients (77%) under T4- and in 18/29 patients (62%) under T3-treatment basal TSH levels were below 0.1 mU/l and levels stimulated with 200 micrograms TRH i.v. were below 0.5 mU/l. 3 patients showed a significant response (to above 0.5 mU/l) in the TRH test despite basal values of less than 0.1 mU/l. In 2 patients with elevated basal TSH levels (0.23 and 0.60 mU/l, resp.) in the IRMAclon, total suppression of TSH secretion was suggested by a failure of TSH to rise after TRH. By retesting these samples in an own TSH IRMA, basal and stimulated TSH values were below 0.1 mU/l. In conclusion, basal and TRH-stimulated TSH levels are well correlated in most patients with thyroid cancer under hormonal treatment. However, in some cases (5/72) determination of basal TSH could not clearly define the degree of thyrotropic suppression. Thus, TRH testing is still necessary to establish definitely complete TSH suppression in patients with thyroid carcinoma under suppressive treatment.
Mann
K
K
Department of Internal Medicine II, University of Munich, FRG.
Saller
B
B
Mehl
U
U
Hörmann
R
R
Moser
E
E
D000230:Adenocarcinoma / Q000097:blood / Q000188:drug therapy; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002291:Carcinoma, Papillary / Q000097:blood / Q000188:drug therapy; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011863:Radioimmunoassay / Q000379:methods; D013964:Thyroid Neoplasms / Q000097:blood / Q000188:drug therapy*; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000627:therapeutic use*; D014284:Triiodothyronine / Q000627:therapeutic use*
D014284:Triiodothyronine; D013972:Thyrotropin; D013974:Thyroxine