Thyroid Dysfunction Associated with Administration of the Long-Acting Gonadotropin-Releasing Hormone Agonist
A 30-year-old female came to the Department of Obstetrics and Gynecology at Cheil General Hospital & Women's Healthcare Center with dysmenorrhea 3 months ago. She received subcutaneous injections of leuprorelin acetate 3.75 mg per month, three times in all, with a diagnosis of uterine myoma and endometriosis. She was examined for thyroid function prior to laparoscopic surgery 1 week ago and she was sent to the Department of Internal Medicine because of thyroid dysfunction. Her blood pressure was 116/76 mm Hg, pulse was 60 per minute, and body mass index (BMI) was 21.9 kg/m2 160 cm, 56 kg. She had no past medical history, but her mother had previously taken medication for hypothyroidism.\nShe had no special symptoms, such as fatigue, weight fluctuation, edema, and gastrointestinal problems. However, she complained of recently occurred sweating and facial flushing. On physical examination, she had slightly diffuse thyroid enlargement and the electrocardiography (ECG) was normal.\nSerum free T4 (fT4, 6.9 pmol/L) was decreased and thyroid stimulating hormone (TSH, 154.4 µU/mL) was elevated. Antithyroglobulin antibody (anti-TG Ab, 100 U/mL) and anti thyroid peroxidase antibody (anti-TPO Ab, 58 U/mL) were both positive, whereas TSH binding inhibitory immunoglobulin (TBII, 4%) was negative. Thus, she started thyroid hormone replacement therapy (levothyroxine 0.1 mg) with a diagnosis of hypothyroidism.\nOne month later, her thyroid function was normalized (fT4, 21.9 pmol/L; TSH, 2.91 µU/mL) and 2 months later, she underwent laparoscopic myomectomy. After the operation, she received injections of leuprorelin acetate three more times; thereafter, her thyroid function was maintained within the normal range. She is currently maintaining levothyroxine 0.1 mg under serial assessment by the Department of Internal Medicine ().