Effect of thyroid state on magnesium concentration of rat tissues.

The effect of alteration of thyroid status by thiouracil (0.1% concentration in drinking water for 60 days) or exogenous thyroxine (25 mg/dg of body weight administered SC from days 30 to 60) on magnesium content of rat tissues following exogenous magnesium was evaluated. Treatment of rats with magnesium solution (25 mg of magnesium sulfate/dg of body weight) resulted in increased magnesium concentration in most tissues of hypothyroid and hyperthyroid rats, with the mesenchymal-derived tissues (aorta, trachea, and ear cartilage) exhibiting the greatest increases (respectively, 154, 130, and 133% of control group values for hypothyroid rats, and 115, 108, and 107% of control group values for the hyperthyroid group). Magnesium concentration in skeletal and cardiac muscle was similar for hyperthyroid and control rats, but magnesium concentration in these same tissues of hypothyroid rats was decreased. Magnesium distribution and retention in rat tissues is altered considerably, depending on the functional status of thyroid gland.