[Diagnosis of thyroid function in premature infants in intensive care]

In 87 premature infants of an neonatal intensive care unit (gestational age 28-37 weeks) serum-T4, -fT4 and TSH were investigated on day 10, 20 and 30 and at term respectively, in addition to the usual TSH-screening (capillary specimen) on day 5. In 47 neonates (54%) T4 and fT4 were found to be low, including all infants under 30 weeks of gestational age and all ventilated infants. Screening TSH was not elevated but in some cases with iodine contamination. 12 of 13 infants in whom TRH-stimulation was performed showed significant response of TSH. We conclude that compromised thyroid function, common in prematures and infants under intensive care, is similar to the euthyroid sick syndrome in adults and does not require therapy. Replacement of thyroid hormone is only indicated in neonates with increased TSH.