Department of Neonatology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China.
Department of Neonatology, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
Front Endocrinol (Lausanne). 2021 Mar 30;11:585956. doi: 10.3389/fendo.2020.585956. eCollection 2020.
At present, the relationship between thyrotropin (TSH) and free thyroxine (FT4) in relation to postmenstrual age (PMA) in preterm infants is still unclear, and there is no reliable standard thyroid hormone reference ranges, resulting in different diagnostic criteria for congenital hypothyroidism been used by different newborn screening programs and different countries.
To investigate the relationship between TSH/FT4 and PMA in very preterm infants (VPIs) born with gestational age (GA) <32 weeks and to derive thyroid function reference charts based on PMA.
A prospective cohort study was performed on VPIs born with GA<32 weeks and born in or transferred to the 27 neonatal intensive care units from January 1, 2019 to December 31, 2019. Serial TSH and FT4 values were measured at the end of each week during the first month after birth and also at PMA36 weeks, PMA40 weeks and at discharge, respectively. The 2.5th, 5th, 50th, 95th, and 97.5th percentiles of TSH and FT4 of different PMA groups were calculated to draw the percentile charts based on PMA.
1,093 preterm infants were included in this study. The percentile charts of TSH and FT4 levels based on PMA were drawn respectively, and the result indicated that the percentile charts of TSH values were gradually increased initially and then decreased with increasing PMA. The 97.5th percentile chart reached the peak at PMA30 weeks (17.38μIU/ml), and then decreased gradually, reaching the same level as full-term infants (9.07μIU/ml) at PMA38-40 weeks. The 2.5th percentile chart of FT4 was at its lowest point at PMA26-27 weeks (5.23pmol/L), then increased slowly with PMA and reached the same level as full-term infants at PMA38-40 weeks (10.87pmol/L). At PMA36 weeks, the reference intervals of the 2.5th to 97.5th percentiles of TSH and FT4 were 1.18-12.3μIU/ml and 8.59-25.98pmol/L, respectively.
The percentile charts of TSH and FT4 in VPIs showed characteristic change with PMA. The results prompt that age-related cutoffs, instead of a single reference range, might be more useful to explain the thyroid function of VPIs. And repeated screening is necessary for preterm infants.
目前，关于早产儿的促甲状腺激素（TSH）和游离甲状腺素（FT4）与胎龄（PMA）的关系仍不清楚，并且没有可靠的标准甲状腺激素参考范围，这导致不同的新生儿筛查计划和不同的国家使用不同的先天性甲状腺功能减退症诊断标准。
研究极早产儿（VPIs）出生时胎龄（GA）<32 周的 TSH/FT4 与 PMA 的关系，并基于 PMA 制定甲状腺功能参考图表。
对 2019 年 1 月 1 日至 2019 年 12 月 31 日期间在 27 个新生儿重症监护病房出生或转来的 GA<32 周的 VPIs 进行前瞻性队列研究。在出生后第一个月的每周结束时分别测量 TSH 和 FT4 的连续值，并在 PMA36 周、PMA40 周和出院时进行测量。计算不同 PMA 组 TSH 和 FT4 的 2.5 百分位、5 百分位、50 百分位、95 百分位和 97.5 百分位，以绘制基于 PMA 的百分位图表。
本研究共纳入 1093 例早产儿。分别绘制了 TSH 和 FT4 水平的基于 PMA 的百分位图表，结果表明 TSH 值的百分位图表最初逐渐升高，然后随着 PMA 的增加而降低。97.5 百分位图表在 PMA30 周时达到峰值（17.38μIU/ml），然后逐渐下降，在 PMA38-40 周时达到与足月婴儿相同的水平（9.07μIU/ml）。FT4 的 2.5 百分位图表在 PMA26-27 周时处于最低点（5.23pmol/L），然后随着 PMA 的增加缓慢增加，在 PMA38-40 周时达到与足月婴儿相同的水平（10.87pmol/L）。在 PMA36 周时，TSH 和 FT4 的 2.5 至 97.5 百分位参考区间分别为 1.18-12.3μIU/ml 和 8.59-25.98pmol/L。
VPIs 的 TSH 和 FT4 百分位图表与 PMA 呈特征性变化。结果提示，年龄相关的截止值而不是单一的参考范围可能更有助于解释 VPIs 的甲状腺功能。对于早产儿需要重复筛查。
