Abstract Background Hypothyroxinemia is defined by low levels of thyroxine (T4) despite or normal thyroid-stimulating hormone (TSH). This study aimed to evaluate the factors associated with transient hypothyroxinemia prematurity (THOP) in newborns admitted neonatal intensive care unit (NICU). Method a single center, retrospective, case-control study. Premature newborns, between 24 and 34 weeks ...

Hypothyroxinemia of prematurity (HOP) is a transient alteration in thyroid hormone availabilityfound in more than half of extremely low birth weight infants (ELBW) born at less than 30 weeks [1]. HOP is characterized by very low total T4 (TT4) and free T4 (FT4) levels with a normal or low thyroid stimulating hormone (TSH); TT4 and FT4 show a nadir at 7-10 days of life and they may remained low ...

Epidemiological studies from both iodine-sufficient and -deficient human populations strongly suggest that early maternal hypothyroxinemia (i.e., low circulating free thyroxine before onset of fetal thyroid function at midgestation) increases the risk of neurodevelopmental deficits of the fetus, whether or not the mother is clinically hypothyroid. Rat dams on a low iodine intake are hypothyroxi...

Sleep deprivation in rats results in progressive declines in circulating concentrations of both total and free thyroxine (T(4)) and triiodothyronine (T(3)) without an expected increase in plasma thyroid-stimulating hormone (TSH). Administration of thyrotropin-releasing hormone (TRH) results in appropriate increases in plasma TSH, free T(4), and free T(3) across experimental days, suggesting def...