iodine supply, after which they start to produce their own thyroid glands. So, definitely in that first trimester, we can see risks and then also again in the third trimester which is when there are massive amounts of foetal growth. And breast tissue development makes a greater call on iodine supply, then obviously for breastfeeding and keeping on moving forward with needing that iodine supply during pregnancy.
IN THE FIRST TRIMESTER OF PREGNANCY, THE FOETUS RELIES SOLELY ON THE MOTHER ' S THYROID HORMONES FOR ITS OWN THYROID DEVELOPMENT AND IODINE SUPPLY, AFTER WHICH THEY START TO PRODUCE THEIR OWN THYROID GLANDS.
Then there are hypothyroid individuals, who are also at an elevated risk of low iodine levels, and lean women generally tend to have lower levels of iodine than obese or women with a higher BMI.
Emma: Ah, so that ' s a key insight.
Miranda: Yes, particularly because we tend to think about lean women as being healthier and that’ s not always the case, is it?
Emma: And are there other patient demographics who might be at risk of acquiring or already having high iodine levels.
Miranda: Yes. And I think this is really interesting: there are particular medications that can increase iodine levels, and one of the big ones is amiodarone, a 200 milligram tablet of which contains about 75 milligram of iodine.
Emma: That ' s so much!
Miranda: Yes, it’ s really high, and amiodarone is a blood pressure medication, and therefore in widespread use. And then in the fertility and IVF worlds, we have to take into account the number of women getting lipiodol flushes. Lipiodol is an iodised poppy seed oil that ' s being injected into the uterus, into the fallopian tubes to flush the tubes and to check tube patency infertility. So, it ' s like hysterosalpingo-contrast. One 10-ml ampoule of lipiodol contains around 4,800 mg of iodine. And the total RDA of iodine even for pregnant women is 200 to 220 mg. Two ampoules of lipiodol are routinely administered: up to 9,600 mg of iodine.
Emma: My goodness. So, do you think that those effects are transient, or could they be problematic?
Miranda: Well, you would hope that they ' re transient, wouldn ' t you? That once a woman has undergone a lipiodol flush, then we’ d be hoping that if they have a sensitivity or a susceptibility to effects with iodine, we would be hoping that they would then just normalise again. But who knows? Maybe it triggers off a whole new set of events.
Emma: That ' s right!
Miranda: And that ' s the thing that we don ' t really know. I mean, lipiodol flushes have not been around for a long time or not commonly used for a long time. And I know some of the IVF specialists are quite aware of the potential increase in iodine they cause, and so of the potential effects onT4 and the thyroid. And then there’ s Betadine.
Emma: Yes, Betadine. The topical, the surgical antiseptics. It also makes me think that the timing of testing with patients who have had exposure to iodine in these ways would be critical.
Miranda: But I don ' t think that we necessarily clinically even think about some of this. We wouldn ' t necessarily think to ask a patient, " Did you fall over yesterday and put betadine on your knee before they ' re going in for a urine analysis of iodine?" These are the sort of things that are no doubt routinely missed.
Emma: Yes, so often and I would put my hand up for that because it ' s not something that ' s on my radar.
Miranda: And not forgetting your other contrast dyes that are used in X-rays and CT scans. I think some of those contrast dyes can contain around 37 grams of total iodine and that ' s high. These are high levels. Particularly when iodine is in microgram doses, we ' re talking milligrams and grams.
Emma: Yes, exactly. And don ' t forget that 2010 Bonsoy dilemma. We’ ve been in practice long enough to remember that.
Miranda: Yes, absolutely.
Emma: For those of you that are not aware, the soy milk brand Bonsoy was formulating their soy milk with a Kombu seaweed extract. And unfortunately, that
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