Disturbed mineral metabolism in hyperthyroidism: good correlation with tri-iodothyronine.

Mineral metabolism is frequently disturbed in hyperthyroidism. In a group of seventy-two patients with hyperthyroidism, we observed an increase in serum diffusible calcium in 50% of the cases, elevated inorganic phosphorus in 30% and elevated alkaline phosphatase in 44% of the cases. Correlations existed between the values of diffusible calcium, inorganic phosphorus, alkaline phosphatase and certain indices of thyroid function (T4, FT41, T3, FT3I), of which that with T3 was the best (P less than 0.001). Our results suggest that the magnitude of the disturbances of mineral metabolism depends on the severity of the hyperthyroidism and that it is the T3 level that constitutes the best index of that severity.