Hello. I need some help understanding these results. Test was done at 2:30 in the afternoon.
50 yo female, with a 5 mm thyroid nodule on left lobe with classic hypothyroid symptoms (tired, cold, joint and muscle pain, thinning hair, depressed mood, constipation).
MD says results are normal.
TSH 1.65 mIU/L (0.32 - 4.00) 36.1% reference range
Free T4 (fT4) 10 pmol/L (9 - 19) 10.0% of reference range
Free T3 (fT3) 3.4 pmol/L (2.6 - 5.8) 25.0% of reference range
T4:T3 Ratio 2.941
TPO antibodies <9 (<35) kIU/L
Limited nutrient analysis available:
Ferritin 23 (15-272)
Hb (118 (120-160)
Hct 0.353 (0.350-0.450)
B12 460 (138-652)
QUESTION: what are the optimal ranges (in percentage through the reference range) for fTs and fT4 for someone not on any medication?
Once I understand this better, if it could help, I will find a clinician in Canada to refer to.
Thanks!
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Joyya
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People with not sort of thyroid problem, and therefore not on any thyroid 'meds', usually have a TSH of around 1 (we don't talk in percentages for the TSH, because a TSH is always a TSH, no matter what the range), and FT4/3 around 50% through the range.
Your FT3 is low, and your FT4 is very low. But as for your TSH, having it done that late in the day would automatically see it low. It would be higher at around 9 am, which is when we normally advise people to have their blood draw. And, if you'd been drinking coffee that morning/lunchtime, that could lower it even further. Doctors world-wide only tend to look at the TSH, even though it's a very bad indicator of thyroid status, because they believe it 'tells them all they need to know'!
Those antibodies are negative, but you also need Tg antibodies tested. And, even if they are also negative, that doesn't not completely rule out Autoimmune thyroiditis.
Your ferritin is also very low, and that would certainly make you tired. And, your B12 is lower than I would want mine. So, that will be contributing to symptoms.
Thanks. Given the T3:T4 is 0.34 based on a blood test at 2:30 PM, and the person has a thyroid nodule and those symptoms, would would be the best next steps?
The time of day doesn't affect the FT4/3, it just affects the TSH. And, the ratio is meaningless, so forget about that. Your FT3 is higher than your FT4 - which is not usually the case - because of the lack of stimulation to the thyroid from the TSH. (Sorry, it's complicated.)
And, as I said, doctors only tend to look at the TSH - which is why we want it as high as possible. Looking at that TSH, even at 9 am, it's doubtful it would be over-range, let alone over 10, which I believe it has to be in Canada. So, 99.9% of doctors would probably say there was nothing wrong with this thyroid.
However, if you manage to find one that understands something about the relationship between the thyroid and the pituitary, they might realise that with such a low FT4 - not to mention the low FT3 - the TSH should be much higher. It would appear that there is a problem with the pituitary, rather than the thyroid itself. Forget about the nodule, they are very common and rarely cause any harm. But the symptoms are suggesting hypothyroidism, due to the low FT3.
So, the next step is finding an endo that knows about pituitaries. And those are pretty rare. So, failing that, it would mean waiting until the FT4 - and possibly the FT3 - fall below range before anyone will take any notice.
That's not very good news, I know, but that's the way the thyroid world works, I'm afraid.
Thank you very much! This is very helpful. I looked further and this person was taking supplements taking biotin, so the TSH results and fT3 results would have been affected, so will recommend that they ask their doctor to have the panel run again after 3 weeks with no B-supplements (I am recommending no supplements) and to have the test done fasted and at 9:00 AM. In the meantime, I will ask some fellow clinicians / MDs I know if they can recommend an Endo to refer her to. Thank you very much for your time and help.
Actually, you can't be sure that the results were affected by the biotin. And, if they were, you can't know which ones, nor how they were affected. But, it is sensible to get retested, and tested early morning. Then the person will have a better idea of where they stand.
Interesting that you say the time taken doesn't affect FT4 and FT3. Having done two private tests over three years showing possible central hypo with 'normal' TSH but increasingly low FT4 and FT3, I just saw an endo who tested mid-afternoon and both were much higher than expected (TSH still normal of course). Other things may have changed too, but I was planning on retesting using same lab and time as first two tests, just to be sure that it was neither food nor time of day that had affected the result and that things have actually shifted. Thyroid Patients Canada seems to imply that those with stronger circadian rhythms may be considerably different during the 24 hours, although it seems that a (healthy) mid-afternoon FT3 would go down rather than up. Cheers
Well, time of day does affect FT4/3 to a certain extent, but not nearly as much as the TSH. But that is in people with a fully working thyroid. Not people on thyroid hormone replacement. If you're on levo and/or T3, it would depend on dose, absorption, conversion and timing of last dose, etc.
I fall between the gap - not a fully working thyroid but not on any medication. Was hoping that the endo might change that but results have changed so now seems unlikely. Thanks for reply.
Yes, the private tests that I did were at 9, fasting, off supplements. That is why I plan to do one more set with those same conditions, just to verify the endo's afternoon, not fasted set. TSH is not appropriate for level of hormones and hadn't been mid 2018 - end 2021, but something seems to have altered that (hormones up, not TSH).
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