Intra-amniotic thyroxine (T4) absorption by the premature human foetus.
We reported previously on the beneficial influence of intra-amniotic T4 injection in accelerating human foetal lung maturity. Twenty-four h after T4 (250 microgram) intra-amniotic injection, the mean cord serum T4 concentration in 13 premature newborns was 17 +/- 2.1 microgram/100 ml, while the T4 concentration in a matched group was only 11.6 +/- 0.9 microgram/100 ml: in 5 of the infants who received intra-amniotic thyroxine T4 was measured 12 h post-partum and rose from 16.1 +/- 1.8 to 24.3 +/- 2.6 microgram/100 ml. No change in maternal T4 concentration was observed. The mean cord serum T4 concentration in premature newborns delivered more than 3 days following T4 intra-amniotic injection, however, was not significantly different from that of the controls. These data suggest that T4 (250 microgram) injected intraamniotically is absorbed by the premature human foetus. Furthermore, the hyperthyroxinaemia is only transient, and does not prevent the post-natal T4 surge.
D000042:Absorption; D000650:Amnion; D005260:Female; D005312:Fetal Blood / Q000032:analysis; D005333:Fetus / Q000378:metabolism*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007267:Injections; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D011248:Pregnancy Complications / Q000097:blood; D013974:Thyroxine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism*
D013974:Thyroxine