Correlation Analysis Of Thyroid Function With Physical Development And Neurodevelopment In Premature Infants Of Different Gestational Ages

Thyroid hormone is an essential hormone in human growth and development.It is an important hormone to maintain the normal basic metabolism and promote growth and development.With the completely opening of the national"two child policy",the birth rate of premature infants is increasing year by year.The organs’development of premature infants is slower than that of full-term infants in the neonatal period.It causes the premature infants are often accompanied with a variety of complications,especially the dysfunction of hypothalamus pituitary thyroid axis which disorder the thyroid function of premature infants,leading to hypothyroidism in premature infants.The deficiency of thyroid level will not only affect the physical development of newborns,but also affect the neural development.It will cause irreversible damage if the deficiency is not corrected in time,leading to short stature and mental retardation and increasing the burden of family and society.Therefore,timely detection early treatment and heteropathy of thyroid dysfunction are of positive significance for physical and neurological development of premature infants,that can help to improve the prognosis of children.However,clinical researchers focus more on the treatment of premature infants at present,and pay less attention to the effect of premature birth on organ function and growth and development of children.In addition,due to the particularity of preterm infants,it is difficult to determine the“normal”thyroxine levels of preterm infants in different disease conditions and different stages of development,and the differences of thyroid function in preterm infants of different gestational ages and their effects on neonatal physical and neurological development are still unclear.Based on this,the aims of this study is to explore the relationship between thyroid function and physical development,neurodevelopment of premature infants with different gestational age.Objective:Serum samples were collected to detect the thyroid function indexes including free triiodothyronine（FT3）,free thyroid hormone（FT4）,and thyroid stimulating hormone（TSH）of infants on the 7 day and 14 day postnatal.Then the correlation analysis of between the levels of thyroid function indexes and the physical growth items and the neurodevelopmental scores on 7 day postnatal of the infants.The aim of the study is to understand the characteristics of the changes of thyroid hormone levels in preterm infants with different gestational age and the relationship between the levels and the health Objective to explore more evidence-based medicine basis for the establishment of diagnostic criteria of transient hypothyroidism（THOP）in premature infants,and to provide basis for the selection of the best time of intervention.Methods:106 premature infants born in the First People’s Hospital of Jingzhou from January 2018 to June 2020 were selected.They were divided into three groups:Group A(28～31⁺⁶weeks),Group B(32～33⁺⁶weeks)and group C(34～36⁺⁶weeks).30healthy full-term infants（37～40weeks）born in the same period were selected as the control group.The above cases were confirmed by the hospital ethics committee approval and their families signed the informed consent.1.5 m L of venous blood was extracted from all the four groups on the 7th and 14th day after birth,and thyroid function（TSH,FT3,FT4）was detected by chemiluminescence immunoassay.Physical development and neurobehavioral test were carried out by specialists.Thyroid function,body development and neurodevelopment were compared,and the correlation between thyroid function and physical development and neurodevelopment was analyzed.Data statistics:SPSS 25.0 was used in this study software,thyroid function index level,physical development index level,nerve development index level as the measurement data,expressed as（mean±standard deviation）,multiple groups were compared using one-way ANOVA,pairwise comparison using LSD pairwise comparison,paired data using paired t test,correlation analysis using Spearman correlation analysis,P<0.05 for the difference was statistically significant significance.Results:（1）Compared with the control group,the levels of FT3 and FT4 in group A,B and C were significantly lower on the 7th and 14th day（P<0.05）;the levels of FT3 and FT4 in group A were significantly lower than those in group B and C（P<0.05）;the levels of FT3 and FT4 in group B were significantly lower than those in group C but higher than those in group A（P<0.05）;the levels of FT3 and FT4 in group C were significantly higher than those in group A and group B（P<0.05）,there was no significant difference of TSH between the four groups on the 7th and 14th day.（2）The levels of FT3 and FT4 in group A,B and C on the 7th day were lower than those on the14th day（P<0.05）;the level of TSH in group A,B and C on the 7th day and the 14th day had no statistical difference;the indexes of thyroid function in the control group on the 7th day and the 14th day had no statistical difference.（3）The birth weight,body length and head circumference of premature infants were significantly lower than those of full-term infants.（4）The neurobehavioral scores of group A,B and C were significantly lower than those of control group（P<0.05）;the neurobehavioral scores of group A was significantly lower than that of group B and C（P<0.05）;the neurobehavioral scores of group B was significantly lower than that of group C.（5）FT3and FT4 were positively correlated with body weight,body length,head circumference and neurodevelopmental scores（P<0.05）;There was no correlation between TSH with body weight,body length and head circumference and neurodevelopmental index scores.Conclusion:（1）The levels of T3 and T4 in preterm infants with different gestational ages decreased significantly,and the lower the gestational age,the more obvious the decline;with the development of preterm infants,the level of thyroid function gradually increased.（2）The physical development level of preterm newborns is lower than that of full-term newborns,and the smaller the gestational age is,the worse the physical development is.（3）The neural development level of preterm infants is lower than that of full-term newborns,and the lower the gestational age is,the worse the neural development is.（4）The level of thyroid function in preterm infants is related to growth and neurodevelopment.