Background: Preterm infants presented a high prevalence of congenital hypothyroidism (CH), while the optimal screening pattern is still under debate. This study aimed at evaluating the characteristics of thyroid function by conducting weekly screening during the first month of life in very preterm infants (VPIs) to achieve timely diagnosis and treatment of CH. Methods: A prospective cohort study was carried out on VPIs born with gestational age (GA) <32 weeks (w) and admitted to the participating institutes from January 1, 2019 to December 31, 2022. Serial serum thyroid hormone levels were measured weekly within the first month after birth, and at 36 w of corrected age, or before discharge. Datasets for serial thyroid hormone levels and general information were obtained. Results: A total of 5992 VPIs were enrolled in this study, of which 456 (7.6%) [95% confidence interval (CI), 6.9-8.3%] were diagnosed with CH. The incidence of CH increased with lower GA, moving from 4.8% [CI, 3.4-6.1%] at GA 31 w to 16.9% [CI, 8.3-25.4%] at GA <26 w. Among the CH subjects, 57.7% [CI, 53.1-62.2%] were identified after the first screening and classified as delayed thyrotropin elevation (dTSH). With the decrease of GA, the proportion of dTSH also increased, moving from 38.1% [CI, 27.5-48.7%] at GA 31 w to 82.6% [CI, 65.8-99.4%] at GA <26 w. Through conducting weekly screening of thyroid function, it was remarkable that only 42.3% [CI, 37.8-46.9%] of CH subjects were diagnosed during the first screening. The cumulative rate of CH identified by rescreening performed at the second, third, and fourth week was 76.1% [CI, 72.2-80.0%], 90.6% [CI, 87.9-93.3%], and 98.9% [CI, 97.9-99.9%], respectively. Conclusion: The incidence of CH and dTSH both increase with lower GA in VPIs. Dynamic screening of thyroid function by weeks within the first month of life is crucial for the timely diagnosis and treatment of CH in VPIs, and it might effectively reduce the implications of missed diagnosis and delayed treatment. Clinical Trials Registration: ChiCTR1900025234 and ChiCTR2000037918 (Registration number).

中文翻译：

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动态筛查甲状腺功能以及时诊断极早产儿先天性甲状腺功能减退症：一项前瞻性多中心队列研究。

背景：早产儿先天性甲状腺功能减退症 (CH) 的患病率很高，而最佳筛查模式仍在争论中。本研究旨在通过对极早产儿（VPI）出生后第一个月每周进行甲状腺功能筛查，评估其甲状腺功能特点，以实现CH的及时诊断和治疗。方法：对2019年1月1日至2022年12月31日期间入住参与机构的胎龄（GA）<32周（w）出生的VPI进行前瞻性队列研究。每周测量系列血清甲状腺激素水平。出生后第一个月、校正年龄 36 周或出院前。获得了连续甲状腺激素水平和一般信息的数据集。结果：本研究共有 5992 名 VPI 入组，其中 456 名 (7.6%) [95% 置信区间 (CI)，6.9-8.3%] 被诊断为 CH。CH 的发生率随着 GA 的降低而增加，从 GA 31 周时的 4.8% [CI, 3.4-6.1%] 升至 GA <26 周时的 16.9% [CI, 8.3-25.4%]。在 CH 受试者中，57.7% [CI，53.1-62.2%] 在第一次筛查后被鉴定为延迟性促甲状腺素升高 (dTSH)。随着 GA 的减少，dTSH 的比例也增加，从 GA 31 周时的 38.1% [CI, 27.5-48.7%] 升至 GA <26 周时的 82.6% [CI, 65.8-99.4%]。通过每周进行甲状腺功能筛查，值得注意的是，只有 42.3% [CI，37.8-46.9%] 的 CH 受试者在第一次筛查期间得到诊断。通过在第二周、第三周和第四周进行的重新筛查，CH 的累积检出率为 76.1% [CI, 72.2-80.0%]、90.6% [CI, 87.9-93.3%] 和 98.9% [CI, 97.9-99.9] ％]， 分别。结论：CH 和 dTSH 的发生率均随 VPI 中 GA 的降低而增加。出生后第一个月内按周动态筛查甲状腺功能对于VPI中CH的及时诊断和治疗至关重要，可有效减少漏诊和延误治疗的影响。临床试验注册：ChiCTR1900025234和ChiCTR2000037918（注册号）。