Follow-up Study of Preterm Infants with Thyroid Dysfunction after Medication.

OBJECTIVES:To study the effect of levothyroxine sodium tablets on the growth and development and thyroid function in preterm infants with thyroid dysfunction. METHODS:A retrospective analysis was performed for 82 preterm infants who were born in the Department of Obstetrics of the First People's Hospital of Yunnan Province, from January 1, 2013 to December 31, 2017, and these infants were hospitalized after birth in the Department of Neonatology of the hospital. They were regularly followed up to observe growth and development and thyroid function at the outpatient service of the Department of Neonatology. According to thyroid function test results, they were divided into an abnormal thyroid function group (observation group; n=31) and a normal thyroid function group (control group; n=51). The infants in the observation group were given oral administration of levothyroxine sodium tablets, while those in the control group were not given any treatment. The two groups were compared in terms of the physical and intelligence development and thyroid function of preterm infants with various gestational ages (28-<32 weeks, 32-<34 weeks, and 34-<37 weeks) after regular follow-up to the corrected age of 12 months. RESULTS:There were no significant differences in physical development indices (body length, body weight, and head circumference) between the observation and control groups at various gestational ages after follow-up to the corrected age of 12 months (P>0.05). There were no significant differences between the two groups in the scores of each functional area of the Gesell Developmental Scale among the preterm infants with a gestational age of 28-<32 weeks and 32-<34 weeks after follow-up to the corrected age of 12 months (P>0.05). For the preterm infants with a gestational age of 34-<37 weeks, compared with the control group, the observation group had a significantly lower score of gross motor ability at the age of 3 and 12 months, significantly lower scores of fine motor ability, language ability, and adaptation ability at the age of 12 months (P<0.05), and a significantly lower score of personal-social ability at the age of 3 months (P<0.05). However, the score of personal-social ability in the observation group was not significantly different from the control group at the age of 12 months (P>0.05). After 2-4 weeks of treatment with levothyroxine sodium tablets, the thyroid function of the 31 preterm infants with thyroid dysfunction returned to normal. Among the 31 infants, 21 (68%) achieved complete drug withdrawal, with normal results of neonatal screening (100%); 10 infants (32%) failed to achieve drug withdrawal, and only 2 (20%) out of the 10 infants had normal neonatal screening results (P<0.05). CONCLUSIONS:Early diagnosis and reasonable treatment can reduce the impact on growth and development in preterm infants with thyroid dysfunction. Most preterm infants tend to have transient thyroid dysfunction, while those with positive results of neonatal screening are more likely to develop permanent thyroid dysfunction.