Another Example of Why Thyroid Blood Tests Make No Sense on T3 Treatment

For people on T3-Only therapy, thyroid blood tests are often a pointless exercise. 

Thyroid blood tests can be helpful for people on just T4/levothyroxine meds and only then if they actually respond well to the T4.

For those on T3-Only (or mostly T3), signs and symptoms are really the best way to assess the dosing/effectiveness of the T3 treatment.

Blood levels of FT3, and FT4 can be very unrepresentative of actual thyroid hormone action inside the cells, and TSH is really not an indicator for many people on T3 treatment.

For patients who are taking T3-Only, their FT4 will be very low (or near zero). FT3 will fluctuate a lot depending on when the blood draw is done relative to the last T3 dose. But often FT3 is quite high. TSH is usually suppressed.

However, doctors and endocrinologists stiil appear to think that they can use the same approach with blood tests that they do with people on T4 medication. They even these seem to pay attention to TSH. 

Story from a Thyroid Patient that Backs the Above Up

I recently received this someone amusing story from a thyroid patient who recovered their health with T3-Only treatment. It speaks directly to the comments above and I thought it was pretty funny:

"A while back my GP insisted I had a Thyroid Blood Test, as I am on T3-Only.

I tried to warn her that is was a waste of funds.

Result came in and she panicked and the Endo she phoned told her to send me to hospital as a matter of urgency!

I was out doing a 50 mile bike ride - at the time she rang for an ambulance!!!

The same Endo two years later is now prescribing T3-Only, as he finally agreed that I am alive and kicking!

We had a few discussions along the way, but he's prepared now to monitor on symptoms and signs only for now.

Fingers crossed he doesn't change his mind! ‬

Paul, I did sense a certain shift in his attitude and an agreeable trial with me is now under way.

I'm holding my breath, but if this Endo still prescribes T3 after our next meeting in two months time then I get to stay on T3.

I'll keep plugging away to get him to get GP to prescribe in time.

Next year I plan to ride a huge cycle Alpine challenge and raise awareness of T3-Only users who are alive and kicking out there! Training hard already on 'Dynamite T3'‬.

P.S,. Zero FT4 and Zero TSH makes people panic when they don't understand how T3-Only works. The GP didn't get an ambulance in end, she just said it crossed her mind, but was reassured that I was only puffed out from cycling when I answered my phone. I said I had another hill to climb and felt fine!"

What a great story! It made me laugh when I read it the first time.

This is actually a perfect example of why thyroid blood tests often don't make sense, and why signs and symptoms are so much more important for those on T3-Only treatment. Signs and symptoms are also key for those on other thyroid hormones also. Even on natural desiccated thyroid (NDT) or T4 (Levothyroxine, Synthroid) thyroid blood tests are not as important as the way the patient feels and some key signs (measurements like body temperature, heart rate, blood pressure etc.). 

I hope you found this interesting. I know I enjoyed the story that this thyroid patient told me.

Best wishes,


(Updated in February 2019)