Thyroid function in healthy and sick very-low-birth-weight infants--thyrotropin and free thyroxine levels until the sixth week of age.

Hypothyroxinemia in preterm infants without congenital hypothyroidism is associated with developmental delay. Longitudinal information on thyroid function in very-low-birth-weight (VLBW, <1,500 g birth weight) infants is limited: we present data on thyroid function in sick and healthy VLBW infants until 6 weeks of age. Free T(4) and TSH levels routinely obtained on days 14-21 and days 35-49 in 92 consecutive VLBW infants were correlated retrospectively with neonatal morbidity. Free T(4) levels were positively correlated with gestational age; an independent effect of neonatal disease on thyroid function was not detectable. Copyright 2001 S. Karger AG, Basel