Radioactive iodine therapy was used for detection and destruction of remnant normal of malignant thyroid tissue after thyroidectomy for differentiated thyroid gland cancer. To achieve a high level of TSH, discontinuation of levothyroxine is required. Discontinuation of L-T4 causes hypothyroidism, serious adverse impacts on patients, therefore, rhTSH is used. The aim of this study was to evaluate the factors influencing serum peak TSH levels after administration of rhTSH in patients with thyroid papillary carcinoma.

Retrospective review was conducted of 249 patients who underwent total thyroidectomy and subsequent RAI therapy at Kangbuk Samsung Hospital between October 2008 and February 2014. We divided patients into two groups according to the stimulated serum TSH level after administration of rhTSH (Group 1: TSH <30, Group 2: TSH≥30). Clinicopathological characteristics were compared between the two groups.

Serum peak TSH was negatively related to height, weight, BSA, and BMI, and positively related to LBM. A non-significant negative correlation was found between serum peak TSH and body composition.

Patients' weight, height, BMI, BSA, and LBM were not associated with serum peak TSH after rhTSH administration. More pharmakokinetic study of rhTSH is needed in order to find correlation between pharmacokinetic factors and TSH level.