Current studies, find the role of thyroid hormone, thyroxine (T4) in regulating the levels of calcium and phosphorous metabolism in bone, blood and muscle of Indian toad, Bufo melanostictus. Following seven days of thyroxine treatment, the body weight of toad increased significantly at both dose levels as compared to the control values. Thyroxine at lower doses showed a more pronounced effect with respect to the calcium and phosphorous parameters, corroborating the earlier view that the hormone is anabolic at lower doses, at least in poikilotherms. Both calcium and phosphorous in three tissues (blood, bone, muscle) showed higher levels following thyroxine treatment at higher doses. Such an observation possibly points to speculations that the hormone influences their levels by regulating their rate of absorption in the digestive tract or rate of excretion in kidney tubules. Alternatively one might suggest inhibitor of thyrocalcitonin by exogenous thyroxine directly through feed-back control or indirectly via the actions of parathyroid hormone.

Keywords:  Thyroxine (T4 ); Calcium; Phosphorus and Bufo Melanostictus.