T3 over range?

(Carrying on from my recent post-I thought I should maybe highlight this for others)

I am new to T3 and while I knew I had to miss a dose of T4 before testing, I didn't realise the same advice DIDN'T apply to T3 :-(

So my reading of 5.0 (3.1-6.8) is now apparently wrong and should be 7.0-which makes me over-medicated. I feel fine though and don't have any apparent signs of being over. Though my temperature and pulse have both raised they are now both normal and I have no rapid heartbeat or anything.

Any advice please?


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19 Replies

  • I don't think you need worry. I take T3 only and leave 24 hours between my dose and am well. I have had no clinical symptoms for a long time now and have a yearly blood test. I shall give you a link which might be helpful and how doctors used to treat/diagnose us.


    The most important fact when taking thyroid hormone replacements is how the patient 'feels' rather than what the blood test states. Bloods change throughout the day so that's why advice is early morning.

  • Thanks a lot Shaws. I am only slightly over and I feel better than when my T3 was low-that's for sure.

    I am on 125mcg of T4 (100 + 25) and was wondering if/when I should drop some of that,,,or should I leave well alone?

  • If everything is going smoothly don't mess about. If symptoms arise, that's a different matter.

  • Good advice Shaws. I was really chuffed when I saw my T3 was up and my TSH was surprised so nearly had a meltdown when I saw my T3 could be over!! I am calm now :-)

  • Infomaniac,

    You should NOT take T3 before your blood test. T3 can peak in the blood for up to 6 hours after taking a dose which will give a high FT3 value. Leave 12 hours between last T3 dose and blood draw.

    How long did you leave between last T3 dose and blood draw? Your result is 5.0. Why do you think 5.0 means 7.0?

  • It was about 26 hours before I had my T3. Someone kindly did a calculation on here last night for me and said I should multiply my result by 1.4 which = 7.

  • On what basis?

    I strongly suspect that any straightforward calculation (e.g. based on supposed half-life) could very easily be confounded in any individual case.

  • Infomaniac,

    Never heard of that. I was told that leaving 24 hours between last dose and blood draw and extrapolating result by +20% would give an estimate of normal circulating T3 level. I wasn't given supporting evidence. If you use that formula 5 + 20% = 6 so your FT3 remains within range.

  • Brilliant-thanks so much :-) I am sure I'd feel it if I was over medicated but at the moment I still don't feel like I'm firing on all cylinders.

  • Infomaniac,

    You're unlikely to feel over medicated until FT3 is quite high over range. I didn't feel at all over medicated when FT3 was 8.4 24 hours after last dose but it explained why my hair was coming out in clumps!

  • Oh God don't say that Clutter!! I swerved T3 for ages because I was scared my hair would suffer but it's actually improved :-) I think me and Blue Horizon are going to be best buddies!

  • Infomaniac,

    You aren't over medicated so you don't need to retest for a year unless you alter dose or medication.

  • Hi - I struggled a bit with getting my head around timings relative to tests since I take my T3 once per day, but then I came across this which helped clarify for me. What I then did was split my daily dose into 2 and took the 2nd half at 8:30, 12 hrs before test.


    Hope it can help someone

    Gillian xx

  • I stupidly just thought I had to stop everything! Ah well it's a learning curve :-)

  • I do exactly what Startagaingirl did. I take Levo plus T3 (in one dose) before I get up. For a couple of days before the test I split the T3 into 2 doses and took the second dose at 8.30 in the evening so that was 12 hours before my blood test.

  • I plan to do that next time Susie.

  • I've finally come down from 75 mcg per day, to 62.5 and now 50mcg - split into 4 over the day - morning 12.5 mcg, lunch, 12.5, evening 12.5 and bedtime 12.5 - before testing I omit the morning dose.

  • I've always just left 24 hours after t3 and t4 before blood test. If I split t3 for a couple of days before test, do I then still have to multiply result by 1.2 (i.e. 20% increase) to get max amount in blood. My endo has not given me any instructions.

  • beh1 Your endo won't give any instructions, they don't know anything about best time to take thyroid hormone for any test.

    If you want to split your dose before a test, then your last dose of T3 is best taken 12 hours before your blood draw. You don't have to multiply that figure by anything. Clutter mentioned adding 20% if you left it 24 hours.

    If you leave 24 hours then your FT3 result will be lower.

    If you take your T3 too close to the blood draw then because it peaks in the blood 2-6 hours after taking it then you will have a high FT3 as you will be measuring what you've just taken.

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