Qom University of Medical Sciences Journal

Background and Objectives: Studies have shown that changes in the serum levels of sex hormones can influence thyroid gland function. The purpose of this study was to investigate the effect of decreased testosterone after orchidectomy on the serum level of thyroid hormones in male rats.

Methods: In this laboratory experimental study, Wistar rats were divided into 7-animal groups, including control, sham, unilateral orchidectomized, and bilateral orchidectomized. After 10 weeks, blood samples were collected using cardiac puncture method and serum levels of T3, T4, and TSH, testosterone, and DHEA, were measured. Data were analyzed using one-way ANOVA statistical test.

Results: Serum testosterone level significantly decreased in orchidectomized (unilateral and bilateral) rats compared to the control group (p<0.001). Serum level of DHEA significantly decreased in bilateral orchidectomized rats compared to the control group (p<0.05). In the bilateral orchidectomized rats, serum level of T3 had a significant increase compared to the control group (p<0.05), but serum levels of TSH and T4 was not significantly changed.

Conclusion: Findings of this study indicated that considerable decrease in serum level of testosterone results in increased level of serum T3, and accordingly, decreased level of serum testosterone leads to disorders caused by increased serum T3.