These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Maternal to fetal thyroxine transmission in the human term placenta is limited by inner ring deiodination.
    Author: Mortimer RH, Galligan JP, Cannell GR, Addison RS, Roberts MS.
    Journal: J Clin Endocrinol Metab; 1996 Jun; 81(6):2247-9. PubMed ID: 8964859.
    Abstract:
    Placental deiodination of T4 to rT3 has been proposed as the factor controlling materno-fetal transmission of T4. We investigated T4 transfer in the isolated perfused human placental lobule with and without addition of the deiodinase inhibitor, iopanoic acid. T4 (150 nmol/L) in protein-free medium was added to the maternal circuit. Without iopanoic acid, the appearance of T4 in the fetal circuit was very low, with fetal T4 levels reaching only 4.1 +/- 0.84 pmol/L at 6 h. Levels of rT3 rose progressively in both circuits, reaching 28.8 +/- 5.5 nmol/L in the maternal and 12.4 +/- 3.2 nmol/L in the fetal circuit by 6 h. No T3 could be measured in either circuit. Addition of 0.5 nmol/L iopanoic acid to maternal perfusate, however, resulted in significant reduction in the appearance of rT3 [maternal levels, 0.58 +/- 0.06 nmol/L (2% of control values); fetal levels, 0.33 +/- 0.03 nmol/L (2.7% of control values)] and a major (approximately 2700-fold) increase in T4 appearance in the fetal circuit, with fetal T4 levels reaching 10.1 +/- 3.4 nmol/L at 6 h. These results support the hypothesis that placental inner ring (type III) deiodination is a major factor controlling placental transmission of maternal T4.
    [Abstract] [Full Text] [Related] [New Search]