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Thyroid UK
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Low T3 - what to do

I just got my blood test results back from the doctor and my TSH is normal but my T3 is very low. The doctor (whom is dutch) told me they normally don't do anything about this, but after researching myself I see that a lot of people have the same issue as me. My question is what do I do now - do I buy T3 online and start self medicating?

My blood test results:

TSH: 0,72

T4 free thyroxine: 18,2

T3 triiodothyronine: 1,11

7 Replies


Can you post the lab ref ranges for FT4 and FT3 (the ranges are the figures in brackets after results)?


thyroïd stimulerend hormoon (TSH) 0,72 (0.38 5.33 )

T4 vrij thyroxine 18,2 (10 22)

T3 triiodothyronine * 1,11 (1.34 2.73)



If your doctor won't increase Levothyroxine dose to raise FT4 and FT3 I would buy T3 online and self medicate. You should be aware that adding T3 will reduce your TSH and may suppress it beyond what your doctor finds acceptable.

You could start by adding 6.25mcg T3 (a quarter of 25mcg tablet) to your current Levothyroxine dose. If you tolerate the T3 after a couple of weeks you could increase to a second 6.25mcg dose at bedtime. Stick with the 12.5mcg T3 for 6-8 weeks and have a thyroid test, including FT3, before increasing further.



It would have been helpful to mention that you are not on thyroid replacement because it does affect advice given.

Have you had a serious illness or virus recently? That's the usual reason for low T3 and it will normally improve when the illness resolves.

If you have had low T3 for some time and have symptoms of hypothyroidism I would ask your doctor to prescribe Levothyroxine to raise your FT4 and FT3. If your doctor won't, then you might try self medicating 25mcg-37.5mcg Levothyroxine instead of T3 initially.


No serious illness or virus.

I have been trying to gain a normal energy level and loose weight for over a year with help from personal trainer and dietician. After a long struggle and not a big result my dietician recommended me having my Thyroid levels checked - hence the result of low T3. I will try booking an appointment with a different doctor, hoping this will give me more guidance and the help needed to gain my normal energy and weight back.



Starvation diet and extreme exercise can deplete T3 too. If your diet and exercise are moderate then I would try a low dose of Levothyroxine initially. The sources in my PM will also supply Levothyroxine but usually in 100mcg doses so you will need to buy a pillcutter to quarter the tablets into 25mcg doses to start.

1 like

Also get your vitamin levels tested for vitamin D, folate, ferritin and B12. Plus testing for thyroid antibodies

Selenium supplements can help improve conversion of T4 to T3

Vitamin C may be helpful too

Private tests are available in UK


Vitamindtest.org.uk - £28 postal kit

Medichecks Thyroid plus ultra vitamin or Blue Horizon Thyroid plus eleven are the most popular choice. DIY finger prick test or option to pay extra for private blood draw. Both companies often have money off offers.

All thyroid tests should be done as early as possible in morning and fasting. This gives highest TSH and most consistent results

Link about antibodies


Link about thyroid blood tests


list of symptoms off, tick all that apply and take to GP



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