[Lithium thyrotoxicosis. Report of a case and review of the literature]

Abstract

It is known that lithium therapy causes goiter and hypothyroidism in about 8% of cases, particularly in patients with circulating antithyroid antibodies. Rarely, lithium is associated with hyperthyroidism: the relationship seems not to be casual, since hyperthyroidism in these patients is three times that of the normal population. These subjects are affected by a diffuse toxic goiter, with or without ofthalmopathy (the majority), or by multinodular toxic goiter or by a painless thyroiditis. In the first case, lithium acts as an immunostimulating factor, even if the real prevalence of antithyroid stimulating antibodies is not well known in these patients; in the second case, an "escape" mechanism following the hormonal release inhibition, favoured by lithium, can explain hyperthyroidism. In the third case, as in this here described, in which no thyroid map is seen at the scintiscan, a local, inflammatory mechanism is involved, in a similar way of some amiodarone induced thyrotoxicosis.