A Case of Iodine-induced Thyrotoxicosis with Acromegaly / 대한내분비학회지

ABSTRACT

Hyperthyroidism is seen in 3.5-26% of subjects with acromegaly. Hyperthyroidism can be developed by thyroid stimulating hormone (TSH) dependent mechanism in TSH-secreting adenomas with acromegaly or by TSH independent mechanism through the stimulation of thyroid cells by growth hormone (GH). So, confirming the cause of hyperthyroidism is important to treat that. We report a case of a 56-year-old man who had acromegaly with iodine-induced thyrotoxicosis. He took the sea tangle for 4 years because he had constipation. His face and hands indicated acromegaly. Thyroid function test showed that T3 and free T4 were increased and TSH was decreased. Ultrasonography of neck showed diffuse enlargement of thyroid gland and thyroid scan showed decreased uptake of thyroid gland. So we could confirm iodine-induced thyrotoxicosis due to excessive iodine intake. Serum GH and insulin-like growth factor (IGF)-1 were markedly increased and brain MRI showed heterogenous 1 cm sized pituitary mass in right side. Acromegaly was confirmed by brain MRI, pituitary stimulation test and increased level of GH, IGF-1. He stopped iodine intake. After 6 months, T3, free T4 and TSH were normalized and he is waiting for the surgical removal of pituitary adenoma.