Graves' Disease that Developed Shortly after Surgery for Thyroid Cancer
A 41-year-old female.\nPalpitations, heat intolerance, perspiration.\nIn November 2010, 0.5×0.6 cm hypoechoic nodules were found in the right thyroid of a female patient. Fine needle aspiration biopsy was performed. Through the pathology examination, she was diagnosed with papillary thyroid cancer and had robot thyroidectomy on the right thyroid in January 2011. During the postsurgery recovery period, she was found to have clinical features of Graves' disease, and the surgery department sent her to our department for investigation and treatment.\nShe had been taking antituberculous drugs since September as she had been treated for tuberculosis.\nShe drank two to three times a week (one bottle of Soju each time), but never smoked.\nNothing noteworthy was seen.\nHer initial blood pressure was 133/78 mm Hg, pulse 95 beats per minute, respirations 20 breaths per minute, and body temperature 36.4℃. She had a clear level of consciousness without acute signs of disease, but She looked rather sick. The thyroid was not swollen and was painless, and there were no palpable nodules. Also, retraction of the palpebral fissures, proptosis, hyperemia of the conjunctivae, and edema were not observed.\nPeripheral blood was examined and the blood results were white blood cells 7,220/mm3, hemoglobin 13.6 g/dL, hematocrit 41.2%, and platelets 353,000/mm3, while the blood sedimentation rate was 7 mm/hr; therefore, all of the test results were normal. According to the serum biochemical examination, blood urea nitrogen was 13 mg/dL, serum creatinine 0.6 mg/dL, calcium 8.8 mg/dL, phosphorus 4.0 mg/dL, gross protein 7.0 g/dL, albumin 4.0 g/dL, aspartate aminotransferase 25 IU/L, alanine aminotransferase 34 IU/L, and gross bilirubin 0.4 mg/dL; therefore, all of the biochemical results were normal. Meanwhile, the alkaline phosphatase density was elevated (111 IU/L). According to the serum electrolyte examination, sodium density was 144 mEq/L and potassium 4.4 mEq/L.\nBefore the operation, triiodothyronine (T3) was 80 ng/dL (normal range, 65 to 150), free thyroxine (free T4) 1.07 ng/dL (normal range, 0.89 to 1.76), and TSH 1.80 µIU/mL (normal range, 0.35 to 5.50), all of which were in the normal range, but 9 months after the operation, the patient was diagnosed with thyrotoxicosis with T3 363 ng/dL, free T4 2.33 ng/dL, and TSH 0.02 µIU/mL. Meanwhile, there was an increase in thyroglobulin (Tg) 16.6 ng/mL (normally, 1.4 to 78.0), antithyroperoxidase antibody 39.6 IU/mL (normally, 0 to 34), antithyroglobulin antibody (anti-Tg Ab) 335.8 IU/mL (normally, 0 to 60.0), and TSHR Ab 5.44 IU/L (normally, 0 to 1.75).\nIn the thyroid sonogram before the operation, 0.5×0.6-cm sized hypoechoic nodules were found in the right lobe of the thyroid which was a normal size, and there was no sign of increased blood flow (). On thyroid ultrasound after the operation, we could not find any tumor or nodule in the remaining thyroid, but the left thyroid was a little increased in size, the overall phosphorus shade reduced, and the blood flow increased (). However, there was no sign of enlarged cervical lymph nodes in the sonogram either before or after the operation.\nThe patient's thyroid activity examination was normal 1 year before she was diagnosed with thyroid cancer and remained normal just before the thyroid cancer operation. On the preoperative thyroid ultrasound, nothing was noteworthy except for hypoechoic nodules in the right thyroid. However, she was diagnosed with thyrotoxicosis during an examination performed 3 months after the right thyroidectomy. When she was transferred to the surgery department for the operation, her T3 was 226 ng/dL, free T4 2.39 ng/dL, and TSH 0.03 µIU/mL. The surgery department decided to reduce the amount of her levothyroxine from 100 to 50 µg (). Since her condition had not improved at all, she stopped taking the drug, but her condition worsened 3 months later (9 months after the operation) and a blood test was performed, and eventually she was sent to the endocrinology department.\nWhen we considered the clinical features, blood examination results, and ultrasound result, we came to the conclusion that the patient had Graves' disease resulting from the thyroid cancer operation, and we began observing the development of her disease while treating her with carbimazole 20 mg/day and propranolol 30 mg/day. After a month, follow-up tests were performed and we found that her results had greatly improved, with T3 at 177 ng/dL, free T4 1.21 ng/dL, and TSH 0.02 µIU/mL. After 6 months of drug treatment, all the values stabilized: T3 was 102 ng/dL, Free T4 1.14 ng/dL, TSH 2.02 µIU/mL, and TSHR Ab, and she currently comes to the hospital for checkups while taking carbimazole 10 mg/day.