目的:研究早产儿甲状腺激素水平动态变化特征.方法:选取胎龄30～31周、32～34周、35～36周的早产儿各20例；同时入选胎龄37～41周的正常足月儿20例(对照组).比较4组新生儿生后第3天、第7天、第28天血清游离三碘甲状腺原氨酸(free triiodothyronine,FT3)、游离甲状腺素(free thyroxine,FT4.)和促甲状腺激素(thyroid stimulating hormone, TSH)的水平.结果:血清FT3、FT4在早产儿组均呈先下降后上升趋势,而在对照组呈下降趋势,且于生后第7天达稳态.对照组、35～36周组、32～34周组和30～31周组血清FT3水平在出生后第3天分别为(4.4±1.17)mmol/L、(3.33±0.98)mmol/L、(2.55±0.613)mmol/L、(1.79±0.38) mmol/L,组间比较P＜0.05；在出生后第7天分别为(3.18±1.27) mmol/L、(2.35±0.45) mmol/L、( 1.69±0.39) mmol/L、(1.08±0.36) mmol/L,组间比较P＜0.05.对照组、35～36周组、32～34周纽和30～31周组血清FT4水平在出生后第3天分别为(27.54±6.1) mmol/L、(23.73±4.09) mmol/L、(20.04±3.14) mmol/L、(16.33±3.17)mmnl/L,组间比较P＜0.05；生后第7天分别为(21.81±4.84) mmol/L、(16.78±2.2)mmol/L、(14.88±2.1) mmol/L、(11.66±3.42) mmol/L,组间比较P＜0.05.生后第28天,对照组与32～34周组和35～36周组FT3和FT4水平均无显著在差异,3组均高于30～31周组(P＜0.01).血清TSH水平,在30～31周组、32～34周组、35～36周组及对照组出生后均呈下降过程.在出生后第3天32～34周组、35～36周组和对照组的血清TSH分别为(9.13±2.91)mU/L、(6.48±3.46)mU/L、(4.29±1.59)mU/L,均比30～31周组(11.75±3.67) rnU/L低(P＜0.05).出生后第7天,30～31周组、32～34周组的血清TSH分别为(6.13±2.76) mU/L和(5.03±2.24) mU/L均显著高于对照组[2.91±1.62],而35～36周组(3.1±1.33) mU/L与对照组无显著差异.在出生后第28天4组血清TSH无显著差异.结论:早产儿胎龄越大,甲状腺功能越接近足月儿.早产儿出生后随着日龄的增加,甲状腺功逐渐成熟,于出生后4周接近足月儿水平.%Objective:To investigate the thyroid function in premature infants. Methods: A total of 80 infants were included in the study,including 60 premature infants who were divided into three groups according to the gestational age[30-31 weeks of gestational age group(Group 1,n - 20) ;32-34 weeks of gestational age group( Group 2,n = 20) -,35-36 weeks of gestational age group(Group 3,n = 20)],and 20 full-term infants (37-41 weeks of gestational age) as control group . Serum free triiodo-thyronine ( FT3 ),free thyroxine ( FT4 ) and thyroid stimulating hormone (TSH) levels were detected on the 3rd,7th,28th day after birth. Results: In groups of premature infants,serum levels of both FT3 and FT4 firstly decreased and then increased. In contrast,serum levels of both FT3 and FT4 in the control group decreased with time and reached a stable level on the 7th day . The serum levels of FT3 on the third day were (4. 4±1. 17) mmol/L in the control group,(3. 33 ± 0. 98) mmol/ L in group 3,(2. 55 ± 0. 613) mmol/L in group 2 and (1. 79 ± 0. 38) mmol/L in group 1 (P<0. 05); on the 7th day,they were (3. 18 ±1.27) mmol/L,(2. 35 ± 0. 45) mmol/L,(1.69 + 0.39) mmol/L,(1.08 ±0.36) mmol/L,respectively (P<0. 05). Similarly,the serum levels of FT4 in the control group,Group 3,Group 2 and Group 1 on the third day were (27. 54 ± 6. 1) mmol/L,(23.73 ± 4.09) mmol/L,(20. 04 ±3. 14) mmol/L,(16. 33 ±3. 17) mmol/L,respectively (P<0. 05) ; and on the 7 th day,they were (21.81 + 4.84) mmol/L,(16. 78 ±2. 2) mmol/L,(14. 88 ±2. 1) mmol/L and (11.66 + 3.42) mmol/L,respectively (P<0. 05). On the 28th day,although no significant difference was observed between the control group and Group 2,or control group and Group 3,all these three groups still had significantly higher serum levels of FT3 and FT4 than Group 1 (P<0. 01). Serum TSH decreased in all the 4 groups with time. On the third day after birth,the serum levels of TSH were (9. 13 ± 2. 91) in Group 2,(6. 48 ± 3. 46) in Group 3 and (4. 29 ± 1. 59) in the control group,all significantly lower than that in Group 1 (11. 75 ± 3. 67) (P<0. 05). On the 7th day after birth,the serum levels of TSH were(6. 13 ± 2. 76) mU/L in Group 1,(5. 03 ±2. 24) mU/L in Group 2,and both of them were lower than that in the control group[(2. 91 ± 1. 62) mU/L],while no significant difference was observed between that in Group 3 [(3. 1 ± 1. 33) mU/L] and that in the control group. On the 28th day,no significant difference in serum TSH level was observed among all the four groups. Conclusions: The thyroid func-tion of the premature infants is transiently low. The shorter the gestational age,the lower the thyroid function is and the longer the stress reaction is.
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