RESUMO
BACKGROUND: There is a gap in knowledge about the postnatal growth of thyroid gland in preterm infants. OBJECTIVE: To determine postnatal growth of thyroid gland in preterm infants. METHODS: Thyroid gland volume was calculated in 57 prospectively enrolled preterm infants by measuring serial longitudinal, antero-posterior, and transverse dimensions of thyroid gland with ultrasound. Data were analyzed by using the Wilcoxon and independent t test. RESULTS: There was a significant correlation between thyroid volume (TV) and birthweight (BW) (p = 0.01), and between TV and gestational age (p = 0.02). However, unexpectedly, 12 infants had a decrease in TV between the first and second ultrasounds. Infants with late onset bacterial sepsis had lower TVs on their second ultrasounds than infants without sepsis. CONCLUSIONS: Thyroid ultrasound in preterm infants provides noninvasive and quick approach to determine TV and morphology. TV in preterm infants correlates positively with BW and gestational age. However, postnatal growth of thyroid gland is variable and may seemingly be affected by postnatal factors.