Immunosuppressive treatment for immune thrombocytopenia which masked Graves' disease

A 71-year-old female patient followed primary immune thrombocytopenia (ITP) was admitted to endocrinology unit with excessive sweating. We started methimazole for Graves' disease. Without any additional immunosuppressive treatment, at week 12 of methimazole therapy, thyroid stimulating hormone (TSH) levels returned to normal, and platelet counts rose to tolerable levels. When her hospital records were analyzed, they revealed that a year ago, when she had been diagnosed with ITP, her TSH values had been suppressed. After immunosuppressive therapy, her platelet values were maintained at normal levels, and during her control visits, her TSH levels were measured twice and were within normal limits. We think that immunosuppressive therapy for ITP without considering thyroid function tests may result in a transient euthyroid state, which potentially masks Graves' disease accompanying immunosuppressive therapy and associated recurrent ITP attacks.