Humoral autoimmune phenomena during long-term lithium treatment with special reference to thyroid autoantibodies

Abstract

In a retrospective study, 58 outpatients under long-term therapy with lithium were examined with regard to humoral autoantibodies. Fifty-five schizophrenic outpatients under neuroleptic treatment served as controls. We examined antithyroidal antibodies (TAK, MAK), smooth muscle antibodies (SMA), antimitochondrial antibodies (AMA), and antinuclear antibodies (ANA). In the lithium group there was a significant higher prevalence of antithyroidal antibodies (33%) as compared to the control group (9%). Ten patients out of 19 patients with antithyroidal antibodies showed MAK as well as TAK; moreover we found a characteristic pattern: MAK greater than or equal to TAK. All lithium-treated patients were euthyroid. Five patients out of the group with antithyroidal antibodies had goiter, three showed temporarily elevated serum concentrations of basal thyroid-stimulating hormone (TSH). We did not find such elevated levels of TSH in the group of eight patients with goiter but without antithyroidal antibodies. There was neither a correlation between the examined parameters and the lithium serum concentration nor the additional psychotropic medication. Our results indicate a significant higher prevalence of antithyroidal antibodies under long-term therapy with lithium as compared to a psychiatric control group. We do not consider these autoimmune phenomena as relevant pathogenetic factors.