Horm Metab Res 2009; 41(10): 762-766
DOI: 10.1055/s-0029-1225629
Animals, Clinical

© Georg Thieme Verlag KG Stuttgart · New York

Effect of Testosterone on Thyroid Weight and Function in Iodine Deficient Castrated Rats

Z. Bahrami1 , M. Hedayati1 , M. Taghikhani2 , F. Azizi1
  • 1Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University (M.C), Tehran, Iran
  • 2Biochemistry Department, Medical Sciences Faculty, Tarbiat Modares University, Tehran, Iran
Further Information

Publication History

received 17.11.2008

accepted after second revision 04.06.2009

Publication Date:
07 July 2009 (online)


The prevalence of goiter, especially in iodine deficient regions, is higher in women than in men. This investigation was conducted to determine the effect of testosterone on thyroid weight and function in both normal iodine deficient and castrated rats. Male Wistar rats were divided into 6 groups of 7 animals each: Castrated hormone treated (C+T); castrated nonhormone treated (C+NT); normal (N), iodine deficient diet, castrated hormone treated (ID+C+T); castrated iodine deficient diet, nonhormone treated (ID+C+NT); and normal iodine deficient diet (ID+N). Three weeks after castration, C+T and ID+C+T groups received daily intraperitoneal injections of 1 mg/kg testosterone enanthate, for 9 weeks. At the end, we measured thyroid weight and serum testosterone, T4, free T4, T3, and TSH, and urinary iodine concentrations. Serum testosterone level significantly decreased in the C+NT and ID+C+NT groups (p<0.001). In ID groups, serum TSH, T3 and thyroid weight levels increased significantly and serum T4 and free T4 levels decreased significantly as compared to iodine sufficient groups (p<0.001). ID+C+NT group, had higher serum TSH and thyroid weight and lower serum-free T4 than the ID+C+T and ID+N groups (p<0.01). The C+NT group had higher serum TSH and lower serum-free T4 than the C+T and N groups (p<0.01). These results suggest that testosterone decreases thyroid enlargement and prevents the fall in free T4 levels in ID castrated rats, which may explain the lower incidence of goiter in men than women in iodine deficient regions.



F. Azizi, MD 

Professor in Internal Medicine & Endocrinology

Endocrine Research Center

Research Institute for Endocrine Sciences

Shaheed Beheshti University of Medical Sciences

PO Box 19395-4763



Phone: +98/21/2240 93 09

Fax: +98/21/2243 62 64

Email: [email protected]