Effect of plasmapheresis and steroid treatment on thyrotropin binding inhibitory immunoglobulins in a patient with exophthalmos and a patient with pretibial myxedema.

The effect of prednisone treatment and plasmapheresis was studied in two patients with Graves' disease complicated by severe exophthalmos and/or pretibial myxedema. Titers of Thyrotropin Binding Inhibitory Immunoglobulins (TBII), Long Acting Thyroid Stimulator (LATS), antithyroid antibodies, and serum gammaglobulin concentrations, as well as clinical changes in exophthalmos and pretibial myxedema, were observed during the course of treatment. Steroid treatment lowered all of the abnormal antibody titers. Plasmapheresis did not change the TBII activity when determined using a fixed amount of immunoglobulin G fraction. However, serum gammaglobulin concentration was reduced by plasmapheresis, and therefore, total TBII activity in a unit of serum was reduced. Plasmapheresis also partially and temporarily resolved the pretibial myxedema, whereas no significant change in exophthalmos was observed. These results suggest that both steroid and plasmapheresis treatment are useful for lowering abnormal antibody titers in sera of patients with Graves' disease, and that plasmapheresis can be of some value in the treatment of pretibial myxedema.