Thyroid Dysfunction Associated with Administration of the Long-Acting Gonadotropin-Releasing Hormone Agonist
A 35-year-old female came to the Department of Obstetrics and Gynecology at Cheil General Hospital & Women's Healthcare Center with sterility 6 months ago. In the past medical history, she had been treated with medication for hyperthyroidism and had underwent surgery for endometriosis. She had received subcutaneous injections of leuprorelin acetate of 3.75 mg per month, three times in all, as a pretreatment for in vitro fertilization from 2 months ago. Since she had a past history of hyperthyroidism, she was refered to the Department of Internal Medicine for further evaluation.\nHer blood pressure was 118/79 mm Hg, pulse was 79 per minute, and BMI was 18.6 kg/m2 (159 cm/47 kg). She had been diagnosed with hyperthyroidism a decade ago and had taken methimazole 10 to 2.5 mg until 3 months before she came to our hospital because her thyroid function was normalized. She also underwent surgery for endometriosis at another hospital 1 year ago. Nothing was noteworthy in her family history.\nShe complained of sweating, heat sensation intolerance, and facial flushing. On physical examination, she had slightly diffuse thyroid enlargement and the ECG was normal.\nSerum T3 (120.6 ng/dL), fT4 (21.8 pmol/L), and TSH (0.51 µU/mL) were all whinin the normal range, but anti-TG Ab (13 U/mL), anti-TPO Ab (>100 U/mL), and TBII (22%) were all positive. Thus, further observation was required.\nOne month later, she complained of palpitation and fatigue, while T3 (259.5 ng/dL) and fT4 (60.6 pmol/L) were elevated, TSH (<0.01 µU/mL) was suppressed, and anti-TG Ab (17 U/mL), anti-TPO Ab (>100 U/mL), and TBII was elevated to 27%. Thus, she was diagnosed with hyperthyroidism and started taking methimazole 10 mg. Two months later, T3 (304.0 ng/dL), fT4 (57.0 pmol/L), TSH (<0.01 µU/mL), and TBII was elevated to 37% and medication was changed to propylthiouracil 200 mg. Three months later, she is currently maintaining propylthiouracil 100 mg under serial assessment by the Department of Internal Medicine ().