The Exchange of Radioiodine in Pregnant and Fetal Sheep

Sa, Book; Hg, Wolf; Hr, Parker; Lk, Bustad

doi:10.1097/00004032-197406000-00007

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…injection into the mother the I3'I concentration ratios in the three metabolic compartments maternal blood: fetal blood: amniotic fluid were 1 : 3.5 : 11. The concentrations in the above mentioned metabolic compartments were 1 : 16 : 69 when '251 was injected in fetal blood and 1 : 5: 55 when injected in amniotic fluid (BOOK et al, 1974). In the former cases, the origin of radioiodine in the amniotic fluid is unknown.…”

Section: Zodinementioning

confidence: 98%

“…Radioiodine which is not accumulated by the fetal thyroid gland but excreted in the amniotic fluid may be taken up by the foetus and thus increase the effective iodine pool of the foetus by roughly 25 Yo (BOOK et al, 1974). As far as the transfer mechanism is concerned, anorganic iodine may freely cross the placenta in both directions before the onset of thyroid function.…”

Section: Zodinementioning

confidence: 99%

See 1 more Smart Citation

Transplacental Transfer of Radionuclides. A Review

Zallinger

Tempel

1998

Journal of Veterinary Medicine Series A

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Transplacental transfer of tritium (H), cesium (Cs), iodine 0, strontium (Sr) and plutonium (Pu) has been observed in all examined species with an active transfer mechanism for iodine, strontium and plutonium. Cesium and tritiated water freely cross the placenta and are dstributed approximately uniformly in maternal as well as in fetal tissue. In pregnant mice, "' Cs concentrations in maternal organs were U j times higher than in the foetus. With increasing weight, Cs amounts rise in the foetus. "'I distribution in the foetus before and after the beginning of thyroid function is totally different. In an 8-week-old human foetus, there was almost no accumulation of "'I in the thyroid gland, while on week 14 of gestation more than 40 YO of the fetal iodine was accumulated in the thyroid gland. Radioiodine given only once results in distinctly higher fetal-maternal ratios than after long-term exposure. Experiments performed to evaluate the extent of placental barrier of Sr in comparison to Ca showed a maximum of Sr/Ca discrimination early in pregnancy while at the end of pregnancy Sr and Ca are transported to almost equal proportions across the placenta. A well-known phenomenon is the accumulation of Pu in the yolk-sack of rats such that 80% of the total activity is contained in the feto-placental unit. For the extrapolation of results from animals to man, experiments should not be confined to laboratory animals but include primates. Furthermore, computer softwares like MIRDOSE could be used to simulate transplacental distribution.

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Section: Zodinementioning

confidence: 98%

Section: Zodinementioning

confidence: 99%

Transplacental Transfer of Radionuclides. A Review

Zallinger

Tempel

1998

Journal of Veterinary Medicine Series A

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“…The results of the present study are rather unexpected, as the few studies examining the iodine concentration in amniotic fluid found that it was influenced by environmental iodine. Animal studies using a double tracer with I 131 and I 125 showed a rapid exchange between the mother and the fetus and between the fetus and the amniotic fluid, suggesting that amniotic fluid could act as an iodine reservoir for the fetus ( 4 ) . Etling et al ( 5 ) examined 218 samples of amniotic fluid collected at varying times during pregnancy and found high levels of iodine in women who had undergone urographic studies with iodized contrast material or who had been exposed to iodized agents intravaginally.…”

Section: Discussionmentioning

confidence: 99%

“…Animal studies have demonstrated a rapid exchange between the mother and fetus and between the fetus and the amniotic fluid, suggesting that the amniotic fluid could act as an iodine reservoir for the fetus ( 4 ) . Etling et al ( 5 ) found high levels of iodine in the amniotic fluid of women who had undergone urographic examinations with iodized contrast materials or who had been exposed to iodized agents vaginally.…”

mentioning

confidence: 99%

Amniotic fluid iodine concentrations do not vary in pregnant women with varying iodine intake

Garcı́a-Fuentes

Gallo²,

Garcia³

et al. 2008

Br J Nutr

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Iodine deficiency is an important clinical and public health problem. Its prevention begins with an adequate intake of iodine during pregnancy. International agencies recommend at least 200 mg iodine per d for pregnant women. We assessed whether iodine concentrations in the amniotic fluid of healthy pregnant women are independent of iodine intake. This cross-sectional, non-interventional study included 365 consecutive women who underwent amniocentesis to determine the fetal karyotype. The amniocentesis was performed with abdominal antisepsis using chlorhexidine. The iodine concentration was measured in urine and amniotic fluid. The study variables were the intake of iodized salt and multivitamin supplements or the prescription of a KI supplement. The mean level of urinary iodine was 139·0 (SD 94·5) mg/l and of amniotic fluid 15·81 (SD 7·09) mg/l. The women who consumed iodized salt and those who took a KI supplement had significantly higher levels of urinary iodine than those who did not (P¼ 0·01 and P¼0·004, respectively). The urinary iodine levels were not significantly different in the women who took a multivitamin supplement compared with those who did not take this supplement, independently of iodine concentration or multivitamin supplement. The concentrations of iodine in the amniotic fluid were similar, independent of the dietary iodine intake. Urine and amniotic fluid iodine concentrations were weakly correlated, although the amniotic fluid values were no higher in those women taking a KI supplement. KI prescription at recommended doses increases the iodine levels in the mother without influencing the iodine levels in the amniotic fluid. Iodine: Amniotic fluid: PregnancyAlthough marked physiological differences exist between the maternal and fetal thyroids, both systems interact through the placenta and the amniotic fluid, modulating the transfer of iodine and small but biologically important amounts of thyroid hormones from the mother to the fetus (1) . Prior to the end of the first trimester, when the fetal thyroid gland and the pituitary-thyroid axis become functional, the thyroid hormones required by the fetus are all obtained from the maternal circulation (2) .The volume and content of amniotic fluid is the result of a balance between the urine and the fetal pulmonary fluids, the amount of fluid that is reabsorbed or swallowed by the fetus (3) and transfer of water and solutes across the fetal membranes.Animal studies have demonstrated a rapid exchange between the mother and fetus and between the fetus and the amniotic fluid, suggesting that the amniotic fluid could act as an iodine reservoir for the fetus (4) . Etling et al. (5) found high levels of iodine in the amniotic fluid of women who had undergone urographic examinations with iodized contrast materials or who had been exposed to iodized agents vaginally. However, few studies have investigated the iodine concentration in the amniotic fluid of human subjects and these only examined the influence of the overload of high iodine concentrations. ...

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“…Thus, the discrepancies between the analytical methods, particularly iodine contamination with free thyroxine, could explain why Davicco et al (1980) (Aumont et al, 1989). (Miller et al, 1967) in bovines (range : 4-6) and in ovines (range : 8-9) (Book et al, 1974 (Dussault et al, 1971(Dussault et al, , 1972Erenberg et al, 1974) or the bovine placenta (Miller et aL, 1967;Hernandez et al, 1972 (Walfish, 1981;Faber, 1984;Laurberg, 1984), the high level of Pll could also be assumed to inhibit the conversion of T4 to T3. Results recorded on ewes (Aumont et al, 1989) have also suggested this hypothesis.…”

Section: Analysesmentioning

confidence: 99%

Iodine nutrition in ewes. 2. Effects of low to high iodine intake by ewes on the I content of biological fluids and plasma immunoglobulins G in newborn lambs

Aumont¹,

Levieux²,

Lamand³

et al. 1989

Reprod. Nutr. Dévelop.

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2. I intake of ewes had no effect on birthweight, body weight gain, or mortality between birth and wk 2 of life. No difference between the groups was recorded in the weights of brain, heart, lungs, and liver of lambs killed at birth. However, the weight of both the thyroid lobes in lambs from group E was lower than that of the other groups. The I content of the thyroid lobes of lambs from group A was 30-40% lower than that of the other groups.3. The plasma inorganic iodine (PII) of lambs from birth to d42 of life was affected by ewe I intake, except for groups A and B, during the first 16 h of life. The Pll of lambs increased with the I intake via milk in each group. The ratio of Pil of lambs at birth/Pll of ewes at d7 prepartum was 3.77, 2.96,

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The Exchange of Radioiodine in Pregnant and Fetal Sheep

Cited by 6 publications

References 3 publications

Transplacental Transfer of Radionuclides. A Review

Transplacental Transfer of Radionuclides. A Review

Amniotic fluid iodine concentrations do not vary in pregnant women with varying iodine intake

Iodine nutrition in ewes. 2. Effects of low to high iodine intake by ewes on the I content of biological fluids and plasma immunoglobulins G in newborn lambs

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