The dose of L-T₄ replacement for hypothyroidism often needs to be increased after pregnancy. In our institution, patients are instructed to double the dose 2 days a week after pregnancy. However, there is scarce evidence supporting the need for a dose increase after pregnancy in patients with preconception thyroid-stimulating hormone (TSH) suppression (TSH <0.3 μIU/mL). This study aimed to determine the need for a dose increase in L-T₄ among women with a TSH-suppressive dose of L-T₄ before pregnancy. In this retrospective observational study, between January 2008 and December 2018, we analyzed 166 pregnancies in 134 patients on TSH suppression treatment after total thyroidectomy for papillary carcinoma. Thyroid function tests were performed before and in the first trimester of pregnancy. The dose was adjusted and maintained during the first trimester of pregnancy in 76 pregnancies (group A) and 90 pregnancies (group B), respectively. The median serum TSH level was significantly lower in group A than that in group B (0.014 μIU/mL (IQR, 0.005–0.071) vs. 0.155 μIU/mL (IQR, 0.021–0.657), p < 0.001). TSH suppression could not be maintained after pregnancy in 15.8% and 38.9% of the pregnancies in groups A and B, respectively. Increasing the post-pregnancy dose by an average of 27.4% resulted in maintenance of TSH suppression after pregnancy in 84.2% of pregnancies. In conclusion, this study suggests that increasing the L-T₄ dose after pregnancy may be appropriate in postoperative thyroid cancer patients whose serum TSH levels should be suppressed.

用于甲状腺功能减退症的 LT ₄替代品的剂量通常需要在怀孕后增加。在我们的机构中​​，指导患者在怀孕后每周 2 天将剂量加倍。然而，几乎没有证据支持孕前促甲状腺激素 (TSH) 抑制 (TSH <0.3 μIU/mL) 的患者在妊娠后需要增加剂量。本研究旨在确定TSH 抑制剂量为 LT _{4的女性是否需要增加 LT 4的剂量}怀孕前。在这项回顾性观察研究中，在 2008 年 1 月至 2018 年 12 月期间，我们分析了 134 名甲状腺乳头状癌全切除术后接受 TSH 抑制治疗的患者的 166 次妊娠。在妊娠前三个月和妊娠头三个月进行甲状腺功能测试。分别在 76 例妊娠（A 组）和 90 例妊娠（B 组）的妊娠前三个月调整和维持剂量。A组中位血清TSH水平显着低于B组（0.014 μIU/mL（IQR，0.005-0.071）vs. 0.155 μIU/mL（IQR，0.021-0.657），p< 0.001)。A 组和 B 组分别有 15.8% 和 38.9% 的妊娠在妊娠后无法维持 TSH 抑制。平均增加 27.4% 的妊娠后剂量导致 84.2% 的妊娠在妊娠后维持 TSH 抑制。总之，本研究表明，对于应抑制血清 TSH 水平的术后甲状腺癌患者，妊娠后增加 LT _{4剂量可能是合适的。}