From the Research
Normal Thyroid-Stimulating Hormone (TSH) Levels in Newborns
Based on Gestational Age
- The normal TSH levels in newborns vary based on gestational age 1, 2, 3, 4, 5.
- For preterm infants born at 22-27 weeks' gestation, the 95th percentile TSH level gradually decreases and reaches a nadir at around 10-11 weeks, with a range of 11-11.8 μIU/mL at 3-4 weeks after birth 1.
- For preterm infants born at 28-31 weeks' gestation, the 95th percentile TSH level reaches a nadir at around 5-6 weeks, with a range of 8.2-9 μIU/mL at 3-4 weeks after birth 1.
- A positive correlation was found between hormonal levels and gestational age, allowing for the definition of a threshold for preterm newborns according to their gestational age 3.
- Premature and low-birth-weight neonates had a significantly higher incidence of congenital hypothyroidism and lower TSH levels compared to full-term neonates and normal-to-high birth weight neonates, respectively 4.
- Neonatal TSH levels are influenced by several factors, including sex, age at collection, prematurity, dopamine use, and birth weight, supporting the use of local sex- and age-adjusted TSH cutoffs 5.