Abstract
Mid-gestation fetal thyroidectomy was performed to study the effect of congenital hypothyroidlsm on the availability and composition of pulmonary phospholipids (PPL) in 8 fetal lambs and 8 sham operated lambs. Amniotic fluid (AF) was collected for baseline thyroxine, thyrotropin, and 3,3'5' tri-iodothyronine. Mean preterm AF lecithin to sphingomyelin (L/S) ratios were 1.15; non-acidic and acidic PPL were 43% and 57% of total. Delivery at term by hysterotomy yielded 2 cretin and 8 normal lambs. Newborn serum studies confirmed hypothyroidism. At term mean normal AF L/S ratios were 1.89 with AF cortisol levels of 1.60 μg/dl. Term cretin AF L/S ratios were 1.56 with AF cortisol levels of 1.3 g/ dl. Lambs breathed for 10 to 30 min., then pharyngeal, tracheal, and gastric contents were aspirated for L/S ratios and PPL assays. Mean normal lamb L/S ratios were 6.66 vs 1.52 for cretins (p<.03). Non-acidic to acidic PPL separation reversed in normal lambs to 63% and 37%; cretins increased the acidic to 69%. Percent postnatal phosphatides in total aspirate PPL were:
Cretin lambs died at 2 hr. of age of profound respiratory failura.
We conclude that congenital hypothyroidism results in the formation of surfactant with an abnormal phosphatide composition and the release of predominantly acidic PPL with poor surface activity.
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Cunningham, M., Hollingsworth, D., Belin, R. et al. IMPAIRED SURFACTANT PRODUCTION IN CRETIN LAMBS. Pediatr Res 11, 424 (1977). https://doi.org/10.1203/00006450-197704000-00330
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DOI: https://doi.org/10.1203/00006450-197704000-00330
