Genes and Your Thyroid: The Missing Piece

So, you’ve finally got the diagnosis: a sluggish thyroid. In Britain, that typically means one thing - you're handed a prescription for levothyroxine, the go-to treatment for hypothyroidism. You pop that little pill, hopeful that life, energy and metabolism will finally turn around.

Fast forward three months. You’re still feeling brain fogged and sluggish, barely making it through the day. You’re cold even when everyone else seems comfortable, your mood has taken a nosedive, and the scale refuses to budge no matter how hard you work out. Your hair? Thinning. Your nails? Brittle as dry twigs.

What on earth is going on?

You make another trip to the doctor, frustration in tow, and explain that the meds aren’t cutting it. With a sympathetic nod, they hand you a slip for yet another blood test. A week later, you call in for the results (because let’s be honest, no one ever calls you), only to be told by the nurse that everything’s ‘Normal—No Further Action Needed.’

You can’t believe it. Back you go to the doctor, armed with your concerns. "The blood tests must be wrong," you insist. You’re foggy-headed, irritable, overweight and cold—basically, you just don’t feel like yourself. This time, your doctor’s sympathy may have dwindled, and you’re met with a dismissive, “Your bloodwork is perfect. Maybe you’re just stressed, busy with work, or getting older. Or perhaps you need more exercise.”

Faulty Meds for Faulty Genes

But here’s the kicker—you might actually be genetically less capable of converting T4, the only thyroid hormone in levothyroxine, into the bioactive T3 hormone that every cell in your body desperately needs. The culprit? A small hiccup on the Deiodinase 2 Gene (aka DIO2). This gene’s little glitch can be a big deal because every single cell in your body has receptors for T3, not T4. This isn’t just about energy levels; it can affect your brain and heart health too.

Now, here’s the frustrating part: the NHS won’t test for this genetic glitch. But if you’re determined (and you should be), you can take matters into your own hands. For about £80, Regenerus Labs offers a test to determine whether or not you’re a carrier of the faulty gene variant. Once you’ve got this evidence, you should be able to convince your NHS doctor to prescribe a combination of synthetic T3 and T4, or, if you have a private doctor, you might be lucky enough to get a prescription for dried pig’s thyroid which contains both T3 and T4, as well as several other thyroid hormones (more on this below).

Genetic Predisposition & Lifestyle Factors

Your genes might also be setting you up for more than just hypothyroidism. There’s a chance they’re putting you at higher risk for Hashimoto’s thyroiditis, an autoimmune condition where your body turns against its own thyroid gland, sometimes destroying it to the point where it’s nearly nonexistent.

Dr. Noel Rose, who helms the Johns Hopkins Autoimmune Disease Research Center, has noted that certain populations, like the Irish, are particularly prone to these genetic quirks. But it’s not just your genes; your lifestyle plays a massive role too. Stress, poor diet, lack of sleep, and insufficient exercise can all tip the scales, pushing you toward Hashimoto’s.

T3 & T4: The End of the Story?

But wait—there’s more to the thyroid story. Some experts argue that synthetic T3 and T4 might not be enough. According to Dr. Alan Christianson, a naturopathic doctor in the U.S., another thyroid hormone, T2, which is derived from T3, plays a crucial role in metabolism. Here in Britain, getting your hands on a full spectrum of thyroid hormones usually means resorting to Natural Dessicated Thyroid (NDT), which isn’t exactly easy to come by. You might need a prescription from a foreign pharmacy or a very cooperative local doctor because NDT isn’t listed in the UK Physician’s Desk Reference. And T2? It’s only available in NDT; there’s no synthetic version.

NDT doesn’t just stop at T2—it contains a whole range of thyroid hormones, from T0 to T4. While conventional wisdom suggests that only T3 and T4 matter, Dr. Christianson’s work implies that T2 might be more important than we realize. Who knows? Future research might uncover that the other thyroid hormones in NDT also contribute to our health in ways we’re just beginning to understand.

From personal experience, I have found that NDT worked best for me. But everyone’s different. Some people do better on synthetic options. We’re all bio-individual, and sometimes a little bit of experimentation is necessary to figure out what works best for your unique physiology.

The Bottom Line

If you’re still feeling rubbish and your GP or endocrinologist insists that your blood tests are perfect, it’s time to find a doctor who listens and understands.

Seek out a practitioner who’s willing to work with you to find the right combination of synthetic T3/T4 or NDT that suits your body’s needs. In many countries, functional medicine doctors are often your best bet, and tend to be the ~33% of American practitioners who prescribe NDT (Hillary Clinton is famously on NDT) while the other 2/3 of American medics prescribe synthetic levothyroxine (Bernie Saunders uses this).

In Europe, continental doctors seem to be more familiar with NDT than their British counterparts, so if you can’t find a physician in the UK who will prescribe you NDT, you may need to consult a continental endocrinologist like Dr Thierry Hertoghe and his colleagues in Belgium to get the care you truly deserve.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3978256/

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4318631/

https://irishamerica.com/2013/08/all-about-autoimmunity-ask-the-expert-dr-noel-rose/

The Complete Idiot's Guide to Thyroid Disease: Clear Information on Causes; Dr. Alan Christianson, Hy Bender

http://www.thyca.org/pap-fol/more/hormones/

Photo credit: Ryoji Iwata, Unsplash