So we already know that thyroid problems can start in utero, right…but a recent Medscape review (the fountain of thyroid information that I frequently drinketh from 😉 ) on Hypothyroidism in childhood taught me a couple of big things I hadn’t known before!
The diagnostic criteria for subclinical hypothyroidism are raised TSH levels in combination with a normal concentration of free serum thyroxine (FT4) but because there are some differences between accepted ranges in TSH assays, high-risk groups should be screened, especially babies with malformations, whose mum received steroid treatment during pregnancy or in the neonatal period, or who had existing thyroid dysfunction, TFTs (or at the least TSH as part of what’s called the Neonatal Screening test) should be repeated 2 weeks later. But now comes the couple of big light-bulb moments: the incidence of eutopic thyroid in twin births is nearly double compared with singletons! As you know, I’m a mother of twins and I’m guessing at 18yrs old now (and multiple peachy TFTs 😉 ) the horse has well and truly bolted for my two but geez…I had no idea of the dramatic increase in risk. And it keeps going…monozygotic twins very commonly show a delayed TSH rise and those numbers are even more prominent in multiple births. The other not-so-fun-fact is the discovery that subclinical hypothyroidism in IVF babies is approx. 10% which is noteworthy considering none were observed in the control group.
This obviously left me thinking “W.H.Y?” And of course…the first place my head goes with the latter…is iodine.
Could this phenomenon in IVF babies be due ultimately to undiagnosed or poorly managed SCH in mum or even simpler still, just basic iodine deficiency, presenting as infertility?!
The reasons behind our increasing rates of thyroid dysfunction across the life-stages are multifactorial (and don’t get me started on the very real contribution of EDCs!) and how, in spite of iodine adequacy being the first thing on the checklist for thyroid health, so many health professionals ignore this, at their patients’ peril… But now at least we know that patients with IVF babies, twins, and preterm bub, who are currently not included in the prioritised screening groups should be…and of course we should keep asking the questions, “what are the mechanisms behind this, why is it so?”
So if this has made you even more curious about the incredible butterflied-shaped gland and you’d like to go for a stroll on the vast plains of “thyroidisms” you can click on this link Thyroid Assessment in Kids and Teenagers and get completely “thyroided” up. There is always more research to come our way so keep your eyes and ears peeled.