Just as optimal integration of lab results into our patient work-ups makes ‘the invisible visible’ we thought we might make visible some of the everyday Q & A that we engage in with wonderful practitioners who are fast becoming Diagnostic Divas & Divos.
Praccie email arrives with subject header ‘Graves Help’ (or is that ‘Graves…HELP!’🤔)
Practitioner: I have a Grave’s patient who required Propylthiouracil (PTU) for a few months from late 2022 until Jan 2023 which obviously took her thyroid in the opposite direction (see labs). Following a miscarriage last year, she has conceived and is around 6/40 and her current TSH result has come in at 3.3mIU/L, her TPO Abs > 1000 and she also has low-level Tg Abs (TRAbs not measured this time) and this is what she just said to me:
“I just had my specialist session this morning – and she has put me on thyroxine (50mcg) as my thyroid is quite low. I also asked her about the prenatal vitamin and she said it was safe for me to be on iodine at this time, as the Graves isn’t present and baby needs it for the development of its own thyroid.”
Oh gawd! Preg? Iodine? Graves? Antibodies? Antenatal or postnatal aggravation?!
Is there an UU30 I can listen to to help me understand this?… sorry for the panicked email…

Rachel: As a general rule, pre-existing Grave’s, if it’s going to aggravate, will do so usually in the first half of pregnancy, it will ease or remit in the 2nd half and raise its nastiest of nasty heads postpartum.  It’s hard to know what of this pattern will apply to your patient given the iatrogenic low thyroid function that she exhibited at the time of conception. So we can agree with the specialist with regard to the Grave’s not being currently active.  And we can also see her HPT has ‘failed’ the necessary adjustment to pregnancy. While the TSH has, as expected, dropped from 8 – 3 mIU/L, reflecting the TSH-like effects of hCG it has not come down enough (<2.5), hence the thyroxine prescription really does make good sense and does not present any risk regarding her Grave’s.
But to your main question…is it safe or sensible to continue her on an iodine-containing supplement, in the form of her prenatal multi?
This is such a good question given a) iodine supplementation would be CI in active Grave’s – because for people with past positive TRAbs and an intact thyroid – relapse lingers around every corner and b) there is some argument (and some emerging but still preliminary evidence) that giving iodine to women who already have TPO/Tg Abs in early pregnancy may increase their risk of post-partum thyroiditis (PPT)!
On the other hand, we are well aware of the heightened iodine requirements for both conception & good outcomes for both mum and bub!
We sure do find ourselves in a few curly clinical scenarios and this is just another one!
Would I personally keep her on iodine? No. Instead, I would try to ensure adequacy through diet esp now.  Keep in mind that the baby is not yet reliant on mum’s iodine per se – but is just using her preformed T4 for the next 5 weeks. And her T4 levels esp with the boost from the thyroxine are sufficient.  At 11wks, the baby will start to produce its own thyroid hormones and that is where mum needs to come good on the iodine supply and her immune system is more greatly suppressed and the thyroid Abs (TPO esp) should 🤞disappear – so this just may be a safer time to supplement 🤔🤓
So while there is some evidence that iodine in TPO and Tg Ab positive patients will increase their risk of thyroid problems postpartum, thyroid supportive inositol (600mg) and Se (83mcg) do no such thing!  This is, in fact,  the only thing that has been shown in these same women to actually prevent and lower the risk of PPT and other postpartum thyroid disasters! So I would be using this little combo all the way…
That’s my quick take – hope it makes sense
You’re so good to me.
Have I told you before how much I appreciate you? I really do!

Have you heard about The UU30 The Thyroid Collective? Over more than a decade, Rachel’s work in thyroid health has gained an enormous following & an impressive reputation for its excellence in quality practitioner education. You may have up-skilled alongside Rachel, undertaking her substantial MasterCourse II in Thyroid & Adrenal Diagnostics or completed smaller instalments on an as-needed basis. Either way, this collection of 10 Update in Under 30 episodes provides you with your very own library of thyroid resources & research summaries on a juicy selection of thyroid presentations, investigations and treatment approaches. These are not new episodes but a curated collection of those previously released which have been reviewed to ensure they stand up in the context of all the new research and we can officially declare them – ‘good to go and full of gold!’

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