ABSTRACT
Objective To investigate the patterns of change in thyroid functional parameters ( serum TSH,FT3, and FT4 ) in patients with papillary thyroid cancer (PTC) before and after the initial 131I treatment for thyroidal remnant ablation. Methods Seventy-four PTC patients, treated with 3.7 GBq 131 I therapy, were divided into two groups, group A with serum TSH＜30 mIU/L and group B with serum TSH ≥30 mIU/L the day before 131I treatment. Five days after the treatment, the patients were re-examined for serum FT3, FT4, and TSH levels.Results In group A (22 cases), 5 days after the 131I ablation treatment, FT4significantly increased by 88% and FT3 by 87%, while TSH decreased by 87% (all P＜0. 05 ), and 45% (10/22)cases manifested the signs of transient thyrotoxicosis. In group B (52 cases)after treatment, individual variance of FT3 and FT4 was obvious,with FT4 decreased by 13% and FT3 decreased by 14% ( both P＜0. 05 ), while TSH slightly increased by an average of 6% ( P＞0.05 ). Conclusion After the initial 131 I ablation therapy for thyroidal remnant, the thyroid hormone levels in some PTC patients significantly increase while in others may slightly decrease in the early stage. The supplementary and suppressive therapy after 131I ablation for PTC patients might be individualized depending on the thyroid hormone determination.