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Why your thyroid function test results may not be giving you the full picture

What’s going on with my thyroid?

You’ve been feeling a little “off” of late. In fact, if you admit to yourself, you’ve been feeling “off” for some time, but you thought that’s just because you’ve been busy at work for what seems like forever.

You feel absolutely shattered and are just about managing to keep going. You’ve noticed that you feel a bit cold… when everyone else around you feels warm. You’re feeling forgetful. Maybe you’re experiencing heavier menstrual periods than normal. And then, of course, there’s that inexplicable weight gain, particularly around the midriff, that won’t budge whatever you seem to do.

You go to your GP and s/he suggests a thyroid function test. The results come back and they’re within an acceptable range, maybe just inside of what’s considered OK. Your GP suggests that you wait and see, and to repeat the tests periodically.

You think it may just be a sign of simply getting older.

But deep down there’s an ounce of you that still thinks that something’s not right.

What next?

First, go back to your GP and ask for your thyroid test results. This isn’t intended to put you on a collision course with your GP, but you need to find out what’s been tested and you need to know the numbers. You’ve a right to request this – it’s your results.


It’s not unusual for standard NHS tests to just test your TSH (thyroid-stimulating hormone) and FT4 (free T4) levels. But, this is not the full picture when it comes to your thyroid health.

Here’s the science bit…(skip to “What to Do” below if you just want to know what action to take)

A healthy thyroid produces two main hormones – thyroxine (T4) and triiodothyronine (T3). Other thyroid hormones are also released, but for now we’ll concentrate on these two as they are the only ones biologically active. T3 is more biologically active than T4.

Release of T4 and T3 hormones into your bloodstream is regulated by your hypothalamus, which sends a signal to your pituitary gland to send thyroid-stimulating hormone (“TSH”) into the bloodstream. TSH then signals to the thyroid to release T4 and T3.

T4 is converted to T3. Note: while the thyroid does produce some T3, the majority of T3 production is from the conversion of T4 to T3. T3 is responsible for weight loss, keeping you warm and in a good mood (i.e. the opposite of low thyroid function).

The issue is that the thyroid function tests routinely cover just TSH and T4 levels and completely miss out on T3 levels.

This means that your T4 levels may show as normal, but if your T4 is not effectively converting to T3 and your T3 levels haven’t been tested … that’s a whole big part of the thyroid equation missing. This is the biggie.

Additionally, your free T4 (“FT4”) and free T3 (“FT3”) levels may also be outside of normal ranges. FT4 is known to cause thyroid issues. Amongst other things, FT3 levels affect your weight, memory, body temperature and energy levels.

Some T4 converts back into reverse T3 (“rT3”). Reverse T3 tells your metabolism to slow down to conserve energy and helps keep your body in balance. However, if you have raised cortisol levels brought about by stress (in all its various guises) or have been crash dieting, your body produces more rT3 to signal to your metabolism to slow down. This can mean that while all your other thyroid hormones test within the “normal” range, you may be exhibiting symptoms of an underactive thyroid. It’s therefore worth considering having rT3 levels tested

Finally, your levels of antibodies against the thyroid (thyroid peroxidase antibodies and thyroglobulin antibodies) should also be checked. This is because in certain instances, the body’s immune system attacks the thyroid gland (known as autoimmune thyroiditis or Hashimoto’s disease).

With Hashimoto’s disease, initially the thyroid steps up hormone production to deal with the attack and moves into overproduction. Eventually the thyroid reaches burn out as it is unable to keep up high production and thyroid cells are destroyed. This can happen over a period of several years, so the earlier you know about it, the more likely you may be able to do something about it.

What to do

Don’t be embarrassed to go back to your GP to request a full thyroid test panel to include:

  • TSH
  • T4
  • Free T4 (FT4)
  • Free T3 (FT3)
  • Thyroid peroxidase antibodies and thyroglobulin antibodies
  • Reverse T3 (rT3)

Note: Not all medical practitioners test reverse T3 levels, but it is suggested to obtain a complete picture.

If your GP is unable to help you, consider having a private clinic test. Check whether the clinic simply provides you with the results or interprets them for you, or whether you will need to go back to your GP for that.

Yes – it will involve paying for it, but consider this: In the UK, around 15 in every 1,000 women experience under-active thyroid function (“hypothyroidism’) and it most commonly women in their 40s-50s that are first diagnosed. So, for the sake of your good health, it is worth obtaining a definite diagnosis to allow you to move forward.

In conjunction with any medical treatment discussed with your GP or endocrinologist, you should look to adopt the lifestyle changes required around nutrition, exercise, de-stressing to support your thyroid and the rest of your hormonal system. These lifestyle changes can absolutely have an impact on current hormone levels. [Spoiler alert: These will be covered in a separate post]

Need some help?

If you would like to connect for a complimentary consultation, then call The FIT Movement on 07946 272615 or email hello@thefitmovement.co.uk to arrange your appointment.

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About: Wendy Goldthorp is the Founder and Director of The FIT Movement. She is a certified 3rd Age Woman Instructor. She works with midlife women from perimenopause, menopause and beyond and supports them in implementing lifestyle and nutrition changes for a positive menopause experience. Wendy is available to work with clients in person and online via Skype.

Disclaimer: This blog is for informational purposes only. It is not intended to diagnose, treat, cure or prevent health problems – nor is it intended to replace the advice of a qualified medical practitioner or health practitioner. No action should be taken solely on the contents of this blog. Always consult your physician or qualified health professional on any matters regarding your health or on any opinions expressed here.