Abstract:

Objective To observe and analyse the changes of related hormone levels after operation or withdrawal of drug (levothyroxine) substitution treatment in patients with differentiated thyroid carcinoma (DTC). Methods One hundred and two patients with DTC were divided into initial treatment without ¹³¹I ablation therapy group (n=33) and multiple treatment with ¹³¹I ablation therapy group (n=69) according to the application of 131I ablation therapy and substitution treatment. Serum thyroid stimulating hormone (TSH), free triiodothyronine (FT3) and free tetraiodothyronine (FT4) levels were detected after operation or 2, 3 and 4 weeks after drug withdrawl. The hormone levels were compared between these two groups at corresponding time points. With serum TSH>30 mIU/L as cutoff point, the attainment rates were compared between these two groups. The relationship between serum TSH, FT3 and FT4 in multiple treatment with ¹³¹I ablation therapy group was analysed, and serum TSH levels and attainment rates were compared among patients with different genders, ages, histological types and clinical stages of tumor. Results Serum TSH levels and attainment rates in initial treatment without ¹³¹I ablation therapy group were lower than those in multiple treatment with 131I ablation therapy group at each corresponding time point, with significant differences at the time points of the third and fourth week (P<0.05). Serum FT3 and FT4 levels were significantly negatively related to FSH level in multiple treatment with 131I ablation therapy group (r=－0.285, r=－0.345, P<0.05). Serum TSH levels and attainment rates of females were significantly lower than those of males (P<0.05), and those of patients >45 years old were significantly lower than those of patients ≤45 years old (P<0.05). However, there was no significant difference in serum TSH levels and attainment rates among patients with different histological types and clinical stages (P＞0.05). Conclusion Serum TSH levels and attainment rates after DTC are lower than those after ¹³¹I ablation therapy. With the continuation of drug withdrawl, serum FSH levels in patients with 131I ablation therapy increase, and FT3 and FT4 levels decrease. Serum FSH levels and attainment rates relate to age and gender of patients.

Key words: differentiated thyroid carcinoma, radioiodine, thyroid stimulating hormone, levothyroxine