极低出生体重儿低甲状腺素血症发生情况及其对生后早期喂养和体重增长的影响

Hypothyroxinemia in very low birth weight infants and its effect on early postnatal feeding and weight gain

目的探讨极低出生体重儿(very low birth weight infant,VLBWI)低甲状腺素血症发生情况、危险因素及其对早期喂养和体重增长的影响。方法回顾性纳入2017年1月至2018年12月北京大学第一医院新生儿重症监护病房收治的164例VLBWI,根据胎龄分为<30周组(85例)和≥30周组(79例),比较组间基本资料及首次检测甲状腺功能情况。根据生后首次甲状腺功能检测的血清四碘甲状腺原氨酸和游离四碘甲状腺原氨酸水平,分为甲状腺素正常组和低甲状腺素血症组,通过单因素和多因素分析对首次检测诊断低甲状腺素血症的危险因素,以及第2次检测甲状腺素的情况进行分析,并根据首次检测及治疗与否,将胎龄<30周和≥30周的VLBWI分为甲状腺素正常亚组、低甲状腺素血症治疗亚组和低甲状腺素血症未治疗亚组,比较组间早期喂养耐受性和体重增长的差异。采用两独立样本/配对t检验、秩和检验、χ^(2)检验和logistic回归进行统计学分析。结果164例VLBWI胎龄(29.7±2.0)周,出生体重(1210±210)g,超低出生体重儿27例(16.5%)。首次甲状腺功能检测日龄为(10.7±3.1)d,低甲状腺素血症发生率为45.1%(74/164),其中轻度71例,重度3例。胎龄≥30周组低甲状腺素血症发生率较高[55.7%(44/79)与35.5%(30/85),χ^(2)=6.883,P=0.009],且3例重度低甲状腺素血症全部出现在胎龄≥30周组。胎龄(OR=1.413,95%CI:1.044~1.912,P=0.025)和男婴(OR=2.082,95%CI:1.047~4.143,P=0.037)是首次检测诊断低甲状腺素血症的危险因素。首次检测甲状腺素正常者,第2次检测时低甲状腺素血症发生率为47.6%(39/82),胎龄≥30周组发生率高于胎龄<30周组[64.5%(20/31)与37.3%(19/51),χ^(2)=5.745,P=0.017]。首次检测诊断低甲状腺素血症者,第2次检测时未治疗组低甲状腺素血症发生率明显高于治疗组[81.3%(26/32)与38.7%(12/31),χ^(2)=11.905,P=0.001]。各胎龄组内比较,甲状腺素正常亚组、低甲状腺素血症治疗亚组和低甲状腺素血症未治疗亚组生后21 d内腹胀的发生率,生后7、14和21 d喂养量和7、14和21 d内体重增长量,差异均无统计学意义(P值均>0.05)。结论VLBWI低甲状腺素血症发生率较高,生后应进行2次甲状腺功能检测以发现延迟出现的低甲状腺素血症。甲状腺素水平及是否治疗对生后早期喂养及体重增长未造成明显影响。

Objective To investigate the incidence of hypothyroxinemia in very low birth weight infant(VLBWI)and its effect on early postnatal feeding and weight gain.Methods This retrospective study analyzed 164 cases of VLBWIs admitted to the Neonatal Intensive Care Unit of Peking University First Hospital from January 2017 to December 2018.According to the gestational age,these VLBWIs were divided into<30 weeks group(n=85)or≥30 weeks group(n=79),and the basic data and thyroid function were compared.According to the levels of serum tetraiodothyronine and free tetraiodothyronine at the first thyroid function test,the subjects were further assigned into normal thyroxine group and hypothyroxinemia group.The risk factors of hypothyroxinemia identified at the first detection were analyzed by single and multiple-facter analysis.The results of the second detection of thyroxine were also analyzed.On the basis of the first detection and receiving treatment or not,the<30 weeks and≥30 weeks groups were divided into normal thyroxine,hypothyroxinemia treated and hypothyroxinemia untreated subgroups,and differences in the tolerance of early feeding and weight gain were compared between different groups.Two independent samples/paired t-test,rank sum test,Chi-square test and logistic regression were used for statistical analysis.Results Out of the 164 VLBWIs with the gestational age of(29.7±2.0)weeks and birth weight of(1210±210)g,27 cases(16.5%)were extremely low birth weight infants.The age at their first detection was(10.7±3.1)d and the incidence of hypothyroxinemia was 45.1%(74/164),including 71 mild and three severe cases,with a higher incidence in the≥30 weeks group comparing to the<30 weeks group[55.7%(44/79)vs 35.5%(30/85),χ^(2)=6.883,P=0.009].All the three severe cases were in the≥30 weeks group.The gestational age(OR=1.413,95%CI:1.044-1.912,P=0.025)and male infant(OR=2.082,95%CI:1.047-4.143,P=0.037)were the risk factors of hypothyroxinemia.At the second detection,the incidence of hypothyroxinemia in VLBWIs with normal thyroid function at their first test was 47.6%(39/82),which is higher in the≥30 weeks group than in the<30 weeks group[64.5%(20/31)vs 37.3%(19/51),χ^(2)=5.745,P=0.017].Among the infants with hypothyroxinemia at the first detection,those untreated had a significantly higher incidence of hypothyroxinemia at the second detection than those treated[81.3%(26/32)vs 38.7%(12/31),χ^(2)=11.905,P=0.001].The incidence of abdominal distension within 21 days,feeding volume on day 7,14,and 21,and neonatal weight gain within 7,14,and 21 days were similar between normal thyroxine,hypothyroxinemia treated and hypothyroxinemia untreated subgroups within the≥30 weeks or the<30 weeks groups(all P>0.05).Conclusions VLBWI is at high risk of hypothyroxinemia.Two times of postnatal thyroid function tests can help to detect the delayed hypothyroxinemia.Thyroxine level and receiving treatment or not may have no significant effect on the early postnatal feeding and weight gain.