What do you call "Normal" Reading for T4?!

Hi All,

My sister has Down Syndrome and underactive thyroid (it runs in the family), she has recently had her annual blood test. I think her medication is too low, what do you think? She is currently on 100 mcg of levothyroxine.

T4 levels is 1.19 (Range 0.27 - 4.2) - No TSH result given, but they are not really accurate. Her result is considered "normal" - no further action, but I beg to differ!

Jen is now 53, low functioning and had just started experiencing having seizures (3 in the last month, the first one on her birthday and she fractured her collar bone). Also will be having an assessment for Dementia this coming Monday. I am going to speak to her GP about her dose, as the thyroid is one of the tests that will be done in the forthcoming assessments. But in your opinion, do you agree with me, that it may be a tad too low in the normal range?

Thanks in advance :)

10 Replies

Personally, I think it's a lot too low. Most people need it up the top of the range to feel well. And, what if she's not converting that T4 to T3? Her FT3 needs testing, too.

The result is likely TSH, FT4 and TT4 have different ranges.

Yes I do, but I will check to see if I was only given TSH level. Mine is 0.54 as I do not make any hormones as I have never had a working gland. I will also see if they check T4 and T3. All the other results seemed normal, but if I am checking the thyroid, I might as well get those results too. B12 deficiency is in our family.

Both myself and our dad (he passed away recently for other reasons but had the condition). I have wondered whether our mum might have been deficient too, but undiagnosed but she did have dementia and with all the talk in the news about it. Makes me wonder. Better be safe than sorry. Thank you everyone for your replies. Much appreciated. :)

JOLLYDOLLY I don't think that is FT4, I think that is TSH. It's definitely the TSH range used by BH and probably Medichecks, also I've seen it given for some NHS results.

FT4 has a much wider range, something like 7-17 or 12-22.

So assuming it's TSH: 1.19 (0.27-4.2) it's in a pretty good place (the ideal generally being around 1 or below for a treated hypo patient) but you'd really need to see FT4 and, if possible, FT3 as well.

I think the result you're giving is in fact TSH, T4 (FT4 or TT4) uses a different range. If so normally you want a TSH of around 1 or below for a thyroid patient. So her's is pretty good. But what matters more is FT3 and FT4 results as those show how the levo is actually being absorbed and converted to T3.

Also would be good to have b12, vit d, ferritin and folate results. Those are often low in hypos and need to be optimized (not just brought in range) for proper hormone conversion and to help rid symptoms. If you have those results please post.

Doctor should check her Free T4 and Free T3. I shall give a link and look at both to see why it these are important.


They rarely do FT4 and FT3 but they should do occasionally anyway and sometimes we don't convert levo to sufficient T3.

Also B12 should be towards the top of the range - around 1,000 to try to prevent dementia and Vit D towards the top of the range, deficiencies in both can cause mental health issues.

Levothyroxine T4, is inactive and has to convert to T3. T3 is the only active hormone and it is required in all of our receptor cells.

Thanks Shaws :)

Definitely get her vitamin D, folate, B12 & ferritin checked. Get the results including ranges (figures in brackets)

Also ask for thyroid antibodies to be tested to see if cause of thyroid is Hashimoto's

Come back here with all the results

That looks like a TSH range, not FT4, in which case it is normal but does not rule out secondary or central hypo. If it is FT4, it's a very weird range and way too low. You need a full thyroid panel - FT4 FT3 TSH and antibodies. If the GP won't do it, get it done privately through Blue Horizon or Medichecks.

Just spoken to the receptionist as I can't talk to the Dr until Thursday evidently!! The silly man, has only checked her TSH level and ferritin levels they seem low to me as well. 87 (range = 30-470). I am worried in case she has a B12 deficiency as it runs in our family aka myself and our late dad! :(

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