Bone and Mineral Metabolism in Hyperthyroidism: An Experimental Study

Abstract

The effect of thyroxine-induced hyperthyroidism on bone and on mineral metabolism was studied in adult, parathyroid-intact and parathyroidectomized dogs. Contrary to the findings in earlier studies, experimentally induced hyperthyroidism was found to cause an increase in bone turnover, an increase in the serum calcium and a decrease in the plasma protein concentrations in both groups of animals. In the parathyroid-intact dogs an additional featurewas the development of hyperphosphatemia. These results establish that the increased bone resorption found in hyperthyroidism is independent of the parathyroid glands. It is suggested that the tendency to hypercalcemia is the result of the increased bone resorption. The change in the serum phosphate concentration may be the result of suppressed parathyroid activity consequent upon the increased mobilization of calcium from bone. (Endocrinology81: 735, 1967)