Abstract
Experimental hyperthyroidism had a negative effect on bone mineral density, but did
not significantly alter mechanical properties of femur and femoral bone thickness.
Estradiol at a dose used in humans for the treatment of osteoporosis decreased seminal
vesicle weight and concentration of testosterone but increased bone density in male
rats compared to intact animals. In these rats, the mechanical analysis revealed an
increased mechanical femur strength higher than the increase in bone density and femoral
cortical thickness. When hyperthyroid male rats with low bone density were treated
with estradiol in spite of a low plasma testosterone, the changes in bone density
resulting from hyperthyroidism were entirely prevented. Estrogens protect the male
skeleton against resorbing action of T3. Treatment with estradiol in male rats with hyperthyroidism did not increase mechanical
bone strength or femoral cortical thickness as it did with estradiol administration
alone. Our results suggest that exogenously administered estrogens may have therapeutic
value in preventing bone loss accompanying triiodothyronine administration, even in
male rats with a low testosterone levels. At the concentration studied, estradiol
increased in spite of low plasma testosterone, bone mineral density, mechanical strength
of femur, and femoral cortical thickness.
Key words
Hyperthyroidism - Bone Mineral Density - Mechanical Strength - Estradiol - Male Rats
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Prof. Dr. P. D. Broulik, M.D.
3rd Internal Clinic · Medical School
U nemocnice 1 · 12808 Prague 2 · Czech Republic ·
Email: pbrou@lfl.cuni.cz
