Transient thyrotoxicosis and hypothyroidism following administration of the GnRH agonist leuprolide acetate

A 45-year-old women with chronic idiopathic thrombocytopenic purpura was gi ven monthly injections of the GnRH agonist leuprolide acetate for the treat ment of uterine leiomyoma. Two weeks after the fifth injection, she showed mild symptoms of thyrotoxicosis. At that time, serum thyroxin (T4) and trii odothyronine (T3) levels were elevated whereas TSH level was suppressed. An ti-thyroglobulin (anti-Tg) and anti-thyroid peroxidase (anti-TPO) antibodie s were positive, whereas TSH binding inhibitory immunoglobulin (TBII) was u ndetectable. Two months later, serum T4 and T3 levels spontaneously decreas ed below the normal ranges. Five months after the onset of the disease, the y returned to normal without any treatment. Anti-TPO and anti-Tg antibodies gradually decreased during the clinical course. Thus, the present case was indicated to be an instance wherein silent thyroiditis developed after leu prolide acetate administration. This is the first report to demonstrate the association of thyroid disorder with leuprolide injection.