Ultrasound and Functional Thyroid Evaluation

Thyroid disorders are most commonly concomitant with prematurity and still remains a controversial topic. The incidence of a temporary form of hypothyroidism among preterm neonates is higher than in the general population. Transient prematurity hypothyroxinemia is defined as a temporary reduction in FT4 values without increase in TSH values. Currently, there is no consensus about normal thyrotropine (TSH) and free thyroxine (FT4) values in preterm infants.

The aim of this study is to determine the volume of the thyroid gland in preterm infants born between 24 and 32 weeks of gestation inborn or admitted to the unit within 14 days from birth and compare it with the results of TSH and FT4 blood concentration. Besides, the objective of the study is to determine values of thyroid hormones in premature infants born before 33 wk gestation to help neonatologist to interpreter the thyroid hormone results

Thyroid disorders are most commonly concomitant with prematurity and still remains a controversial topic. Preterm infants are susceptible to thyroid disorders due to many reasons including immaturity of hypothalamopituitary-thyroid axis, non-thyroidal illness, impaired synthesis and metabolism of thyroid hormones, medication administration like dopamine, steroids, caffeine.The incidence of a temporary form of hypothyroidism among preterm neonates is higher than in the general population. Transient prematurity hypothyroxinemia is defined as a temporary reduction in FT4 values without increase in TSH values. It is a diagnostic challenge in order to differentiate it from thyroid disfunction in the critically ill patient. Currently, there is no consensus about normal thyrotropine (TSH) and free thyroxine (FT4) values in preterm infants. Given the delayed appearance of TSH value increase in preterm newborns additional thyroid evaluation methods are sought. We believe the thyroid ultrasound might prove helpful.

The aim of this study is to determine the volume of the thyroid gland in preterm infants born between 24 and 32 weeks of gestation inborn or admitted to the unit within 14 days from birth and compare it with the results of TSH and FT4 blood concentration. We will performed the thyroid ultrasound to estimate the thyroid volume to aid in the comparative evaluation of infants with suspected thyroid disease. The value of sonography thyroid volume will give specialists possibility to identify a gland as normal, small or enlarged. Besides, the objective of the study is to determine value of thyroid hormones in premature infants born before 33 wk gestation to help neonatologist to interpreter the thyroid hormone results

Eligibility Criteria:
Inclusion Criteria:

* preterm infants born between 24 and 32 weeks of gestation (estimated by ultrasound)
* in born or admitted to the unit within one week from birth
* randomization within 7 days from birth
* parental consent

Exclusion Criteria:

* preterm delivery \<23 weeks of gestation or \> 32 weeks (estimated by ultrasound)
* major congenital abnormalities
* no parental consent
* medications used after birth: steroids, vasopressors (up to 12 hours after end of treatment)
* positive thyroid stimulating antibodies (TSAb) in the mother
* mothers with thyroid disease treated with antythyroid drugs
* mothers treated with amiodarone