Thyroid Disease in Patients with Idiopathic Thrombocytopenia: A Cohort Study

Objectives: To estimate the prevalence of the association between thyroid disease and idiopathic thrombocytopenia (ITP), and to examine the effect of treatment of the thyroid condition on platelet count. Design: Retrospective cohort study performed in a tertiary care center setting. All patients who were diagnosed with ITP by a single provider at the Cleveland Clinic Hematology/Oncology Department between 1988 and 2005 were included. Main outcome: Among the 98 patients, thyroid function tests were available in 80 patients. Of these, 16 (20%) had abnormal thyroid function: 6 had hyperthyroidism and 10 had hypothyroidism. The median interval from the onset of the thyroid or hematological condition (whichever came first) was 84 months (range: 25–612). The autoimmune nature of the thyroid disease was proven in 12 cases (75%). Three patients showed a transient increase in the platelet count after restoring the euthyroid state; however, durable improvement of thrombocytopenia was not encountered. Conclusions: The prevalence of hypothyroidism in patients with ITP is higher than in the general population. Based on this observation, routine assessment of thyroid function should be done in patients with ITP. The long-term course of ITP was not influenced by the treatment of the thyroid condition.