Abstract
We found that the incidence of PDA in 283 preterm infants was increased in those with serum T4 < 6 ug/dl (day 6 value) versus those with T4 > 6 ug/dl (< 1000 g:63 vs 33%; 1000-1250 g:27 vs 0%; 1251-1500 g:13 vs 5%, p < 0.02). To examine the role of thyroid hormones on the ductus arteriosus we used preterm lamb fetuses (118d, term is 147d) and infused them with T3 or saline for 4d (plasma T3 = 303 ± 215 ng/dl, ± SD vs. 18 ± 9 ng/dl; plasma T3 in 1-7 d full term newborn lambs = 400-600 ng/dl). Following the infusion, we studied the ductus arteriosus from 13 fetuses prenatally and 14 fetuses postnatally (following C-section and ventilation for 4.5 h). The ductus was studied in vitro. There were no differences between prenatal ductuses from T3 infused and control fetuses in their contractile response to O2 and indomethacin or relaxation with PGE2. Ductuses studied postnatally from T3 infused premature lambs had a significantly decreased ability to contract and relax versus control lambs. Postnatal ductuses from T3 infused premature lambs behaved like ductuses from postnatal full term lambs, i.e., there was a decreased ability to relax or contract in vitro. The persistence of ductus responsiveness in postnatal premature lambs (with low T3) may account for the increased incidence of PDA in preterm human infants who have low neonatal T3 and T4 concentrations.
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Clyman, R., Breall, J., Maher, P. et al. 1367 THYROID HORMONES AND THE DUCTUS ARTERIOSUS. Pediatr Res 19, 338 (1985). https://doi.org/10.1203/00006450-198504000-01391
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DOI: https://doi.org/10.1203/00006450-198504000-01391