Effects of marginal iodine deficiency during pregnancy: iodide
uptake by the maternal and fetal thyroid..
Versloot, P. M., J. P. Schr[diaeresis]oder-Van Der Elst, D. Van Der
Heide, and L. Boogerd.
Department of Human and Animal Physiology, Agricultural University,
Haarweg 10, 6709 PJ Wageningen, The Netherlands.
APStracts 4:0184E, 1997.
Iodide uptake by the thyroid is an active process. Iodine deficiency
and pregnancy are known to influence thyroid hormone metabolism. The
aim of this study was to clarify the effects of iodine deficiency and
pregnancy on iodide uptake by the thyroid. Radioiodide was injected
intravenously into nonpregnant and 19-day pregnant rats receiving a
normal or marginally iodine-deficient diet. The uptake of radioiodide
by the thyroid was measured continuously for four hours. The absolute
iodide uptake by the maternal and fetal thyroids at twenty-four hours
was calculated by means of the urinary specific activity. Pregnancy
resulted in a decrease in the absolute thyroidal iodide uptake.
Marginal iodine deficiency had no effect on the absolute iodide upta
ke by the maternal thyroid. The decreased plasma inorganic iodide was
compensa ted by an increase in thyroidal clearance. A similar
compensation was not found for the fetus; the uptake of iodide by the
fetal thyroid decreased by fifty percent during marginal iodine
deficiency. This can lead to diminished thyroid hormone production
which will have a negative effect on fetal development, especially of
the brain.
Received 23 May 1997; accepted in final form 12 August 1997.
APS Manuscript Number E232-7.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1997 The American Physiological Society.
Published in APStracts on 27 August 1997