Plasma and erythrocyte magnesium concentrations in thyroid disease: relation to thyroid function and the duration of...

To clarify magnesium metabolism in thyroid dysfunction, plasma and erythrocyte magnesium concentrations (P-Mg, E-Mg) were determined in patients with untreated thyroid diseases and their relations to thyroid hormone levels and the duration of illness were examined. P-Mg was significantly lower in hyperthyroid patients than in euthyroid or hypothyroid individuals. E-Mg was significantly higher in hypothyroid patients than in hyperthyroid or euthyroid individuals. In the entire series of 84 subjects, both P-Mg and E-Mg showed significant negative correlations with thyroid hormone levels, but the correlations were greater in P-Mg than E-Mg. In hyperthyroid patients, both P-Mg and E-Mg were negatively correlated with the duration of illness, but this correlation was greater in E-Mg than P-Mg. Also, both P-Mg and E-Mg were significantly higher in patients with destructive thyroiditis with a short duration (0.5 months) such as subacute or painless thyroiditis than in patients with Graves' disease (4.9 months). These results suggest that magnesium metabolism in thyroid dysfunction is affected not only by thyroid hormone levels but also by the duration of illness.