Confused about blood tests - Advice appreciated - Thyroid UK

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Confused about blood tests - Advice appreciated


Hello, I have spent some time here reading other posts but am fairly new and would really appreciate advice and any thoughts.

On the 18th Jan 2018 my thyroid blood results were:

Free T3 7.5 pmol/L 3.1 - 6.8 (HIGH)

Free Thyroxine 20.4 pmol/L 12 - 22

TSH 2.12 mIU/L 0.27 - 4.2

Ferritin 17.2 ug/L 30 - 400 (LOW)

(I have only recently found that Ferritin is related to the thyroid so this was totally overlooked. I plan to retest Ferritin soon and read up on it)

I decided to test myself because I was showing the following signs and symptoms:

Mild depression, emotional instability, insomnia, difficulty getting out of bed, no libido, memory lapses, brain fog, poor appetite, poor sense of wellbeing, slightly low oral body temperatures.

Clearly my T4 and T3 were high but my symptoms seemed to point to hypothyroidism. I interpreted this as having high rT3 and made the decision to take T3 at 50mcg per day for about 15 weeks to attempt to reduce rT3.

Upon beginning T3, my symptoms improved a lot. All the symptoms mentioned above apart from no libido were more or less gone or greatly improved in the first few weeks. My main hopes were to bring back libido but unfortunately there was little difference in that area. I came off T3 in hopes that my rT3 would be cleared and that I would remain symptom free. As expected I did feel worse for a while but then improved. Improvement took longer than expected. This was during summer.

I am now doing alright. I have just started my first full time job and expected to be very tired but that doesn't seem to be the case. I am not depressed either.

I am not symptom free however; I am having trouble with memory and brain fog which is making things quite difficult at my job, appetite is low, so are temperatures and libido is practically gone.

I got another blood test:

15th November 2018

TSH 1.69 mIU/L 0.27 - 4.2

Free T3 6.62 pmol/L 3.1 - 6.8

Free Thyroxine 19.7 pmol/L 12 - 22

Reverse T3 19 ng/dL 10 - 24

Reverse T3 ratio 22.68 15 - 75

This test has confused me. I don't know a whole lot about rT3 numbers but they are lower than I had expected which puts my theory, that rT3 was the cause of high T3/T4 with hypo symptoms and TSH higher than one, into question. I had planned on taking T3 again but am unsure about this now.

Thank you for reading. I would be grateful for any advice or knowledge about what the problem might be, things I have overlooked and whether my plans to take T3 again should be avoided.

6 Replies

High rT3 does not cause high FT4 and FT3 - nor does taking T3 'cure' high rT3.

There are many causes of high rT3, but one of them is high FT4 and low FT3, because you are not converting. This was obviously not your case because your FT3 was higher than your FT4.

If you're rT3 was high - your don't give us the numbers - then it could have been caused by your low ferritin. In which case, taking a high dose of T3 would not have been the right response. Increasing your ferritin would have been the right response. But, the trouble with the rT3 test is that it tells you if there is a problem, but not where the problem likes. So, not much use. You can judge your conversion rate just by comparing your FT4 and your FT3.

I'm wondering if your have high antibodies - which would mean you have Hashi's. That could cause results like yours. :)

Thyronoob in reply to greygoose

Thank you for the response. Are you saying that taking T3 does not help at all in reducing rT3, or that it can be useful but the root cause should be found instead? If the later; do you ever advocate taking T3 while looking for the cause? I am interested in doing this because I do not yet have the money for comprehensive tests and I hear Ferritin can take a very long time to raise. At this rate, I might not be employed long enough to make the money as I keep forgetting what my boss has asked me to do! :L

I will order another Ferritin test and test antibodies when I can. Will look into Hashi's. Thanks :)

greygoose in reply to Thyronoob

I am saying that if high rT3 is caused by low ferritin, high cortisol, or whatever, then taking T3 isn't going to lower it. How could it?

If, on the other hand, high rT3 is caused by high FT4 and low FT3, due to a conversion problem, then lowering the levo dose, and increasing T3 will lower rT3.

But, then again, the OP didn't say whether she was taking any levo with that high dose of T3. If you stop taking T4 (levo), and your thyroid isn't making any, and just take T3, then the rT3 will drop because there's no T4 to convert to rT3. You can't have rT3 without T4. But, it won't be the T3 that is causing the rT3 to drop, it will be the lack of T4. As soon as you start taking T4 again, the rT3 will start to rise.

Thyronoob in reply to greygoose

Hmm I'm sure I haven't properly grasped things but my understanding was that T4 will convert to either rT3 or T3; when low ferritin, high cortisol etc is present, T4 will convert to rT3 at a higher rate than usual, increasing rT3. So taking T3 would inhibit T4 production, therefore reducing both endogenous T3 and rT3.

I am the OP (male) and was not taking any Levothyroxine. The 15 weeks of T3 was the only thyroid meds I have ever taken.

greygoose in reply to Thyronoob

Well, I was talking about someone on thyroid hormone replacement. You appear to be talking about a normal thyroid. I did say 'if your thyroid isn't producing any T4'.

Sorry, I didn't look back to see the name of the OP. A bad failing of mine. :)

But, do you think your thyroid is still producing hormone?

In any case, yes, you're right, taking T3 only would probably reduce the gland's production of T4, and without T4 there is no rT3, obviously. But, it doesn't solve any sort of problem, because rT3 is not any sort of problem in and of itself. It's just a safety valve. I think that's where our wires got crossed. You think that high rT3 is causing a problem, when in fact, it's the result of a problem. Of course, if you have low FT3, that won't help, and you would be better off raising it. But don't go off at a tangent about rT3, it's a complete red herring. :)

Thyronoob in reply to greygoose

Thanks :) Will get tests done.

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