Does tumor-derived human chorionic gonadotropin act as a thyroid stimulator in vivo?
To evaluate in vivo the proposed intrinsic thyroid-stimulating hormone (TSH) activity (TSA) of human chorionic gonadotropin (hCG), we monitored over 0.5-1 years the thyroid status of eight patients with hCG-producing non-seminomatous testicular cancer. The patients' sera were analyzed for concentrations of hCG, free thyroxine (fT4), hTSH, and thyroxine-binding globulin (TBG). All patients had excessively high concentrations of hCG (1 x 10(5)-5 x 10(8) ng/L, mean: 1 x 10(7) ng/L) before polychemotherapy, which decreased under successful therapy to physiological values (< 240 ng/L). Although the serum concentrations of hCG varied by more than six orders of magnitude, we saw no changes and no correlation (P > 0.05) between the concentrations of hCG and the concentrations of fT4 and hTSH. Not even when hCG concentrations were greatest (> 5 x 10(7) ng/L) were any signs of hyperthyroidism observed: fT4 (3.5-13 ng/L) and hTSH (9-700 ng/L) were in the physiological range in all patients and remained so during chemotherapy. The results of this longitudinal study were confirmed in analyzing the data for all eight patients (total: 82 samples) cross-sectionally. Again, we found no correlation (P > 0.05) between the concentrations of hCG and fT4 or hCG and hTSH. We conclude that even excessive amounts of testicular tumor-derived hCG do not display any TSH-like activity in vivo.
Madersbacher
S
S
Institute for Biomedical Aging Research, Innsbruck.
Schwarz
S
S
Mann
K
K
Klieber
R
R
Wick
G
G
Berger
P
P
D006063:Chorionic Gonadotropin / Q000097:blood / Q000494:pharmacology*; D003430:Cross-Sectional Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D008137:Longitudinal Studies; D008297:Male; D013736:Testicular Neoplasms / Q000097:blood* / Q000188:drug therapy; D013972:Thyrotropin / Q000097:blood*; D013974:Thyroxine / Q000097:blood*; D013975:Thyroxine-Binding Proteins / Q000032:analysis*
D006063:Chorionic Gonadotropin; D013975:Thyroxine-Binding Proteins; D013972:Thyrotropin; D013974:Thyroxine