The clinical characteristics of hypothyroidism after sunitinib treatment in a Korean population / 대한내과학회지

ABSTRACT

BACKGROUND/AIMS: Hypothyroidism is a common side effect induced by sunitinib. Studies have suggested that sunitinib induces destructive thyroiditis or inhibits iodine uptake by the thyroid or anti-thyroid peroxidase activity. Therefore, the amount of iodine intake will also influence the incidence and clinical characteristics of hypothyroidism after sunitinib treatment. We evaluated the incidence and clinical characteristics of hypothyroidism after sunitinib treatment in Korea, an area where iodine is abundant. METHODS: Between November 2005 and July 2007, 25 patients who had thyroid hormone levels measured during or after sunitinib treatment were included. Of the 25 patients, 13 had thyroid function tests (TFT) because they had symptoms suggesting hypothyroidism and 12 underwent TFT independent of symptoms for screening. RESULTS: All 13 patients who had symptoms suggesting hypothyroidism were hypothyroid (9 overt, 4 subclinical), 6 of 12 patients who had TFT independent of symptoms were hypothyroid (2 overt, 4 subclinical), and two had thyrotoxicosis. Of the 19 hypothyroid patients, the 11 overt hypothyroid patients took longer for a diagnosis of TSH elevation (44.5 vs. 14.8 weeks, p<0.05) and had a greater cumulative sunitinib dose (8050+/-3211 vs. 3718+/-1961 mg, p<0.05) compared with the subclinically hypothyroid patients. At the point of detecting TSH elevation, the TSH level correlated with the period and cumulative dose of sunitinib. CONCLUSIONS: The anticipated incidence of sunitinib-induced hypothyroidism is more than 50%. Compared with previous studies performed in other areas, the iodine intake did not affect the incidence of sunitinib-induced hypothyroidism.