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.

Thyroid function in very low birthweight infants after intravenous administration of the iodinated contrast medium iopromide.

BACKGROUND: Thyroid function disorders have often been observed in preterm infants after intravenous administration of iodinated contrast medium. The effect on thyroid function depends on the dosage, but the choice of the contrast medium may be equally important, as there are appreciable pharmacological differences between them. METHOD: Thyroid function was analysed in 20 very low birthweight infants of gestational age less than 30 weeks after injection of iopromide, a monomeric non-ionic iodinated contrast medium. Levels of free thyroxine and thyroid stimulating hormone were compared with those in 26 control infants. RESULTS: Free thyroxine levels in all study infants ranged from 9.0 to 25.7 pmol/l (days 14-21) and 9.0 to 23.2 pmol/l (days 35-49), and thyroid stimulating hormone levels ranged from 0.13 to 0.26 mU/l (days 14-21) and 0.26 to 11.11 mU/l (days 35-49). These levels were not altered after injection of iopromide. CONCLUSION: The risk of transient hypothyroidism or hyperthyrotropinaemia may be reduced with the use of iopromide compared with other contrast media.