The effect of thyroparathyroidectomy: development of disuse osteoporosis in adult rats.

The present investigation was undertaken in order to study the role played by the thyroid and the parathyroid glands in the development of osteoporosis induced by immobilization. One hundred and fifty-three male adult Sprague-Dawley rats were divided into 2 groups. The animals of one group were thyroparathyroidectomized; those of the other group were left intact. Each group was then divided into two subgroups in one of which the right hind leg of the animals were immobilized by elastic adhesive bandages. The animals were observed for varying periods of time up to 16 weeks. Bone mass and composition was determined and the results indicated that disuse osteoporosis occurs in rats in the virtual absence of the thyroid and parathyroid glands. The bone loss of the immobilized femur and tibia is however less pronounced in thyroparathyroidectomized than in intact rats.