When to take medication for T3/T4 combination medication ahead of testing

[Buttercupsareyellow]

I have seen lots of posts about blood tests, and needing to take last dose of levothyroxine 24 hours ahead of them (which I’ve always done) and waiting around 12 hours if on T3.

My question is:

I have now seen a private endo who agreed to a trial of ERFA (mix of T4 and T3) in lieu of some of my levothyroxine. I started on 30 (half grain) in place of 50 of levothyroxine, just increased to 60 (one grain) to replace 100 Levo.

I gambled on waiting the 24 hours with both meds as there is some T4 in the ERFA. For first time in 15 years my bloods were nearly normal on 30 dose add in and bloods done in this way:

TSH 0.23 (0.27-4.2)

T3 4 (3.1-6.8)

T4 16.8 (12-22)

Previously my TSH began with a 0.0 something eg 0.02, 0.08 at the most and my T4 was 21-23.

I still feel T3 is low and endo obviously agrees as he has increased ERFA dose. Also concerned T4 might be a bit low for me, especially if my T4 will effectively be dropping again.

So, question: if taking the ERFA which is MIX of T4 and T3 do you do as I did and follow the T4 rules for blood testing or should I have followed the T3 rules and taken that tablet 12 hours before?

Wasn’t sure if that might have been the cause of T3 still being low?

Would value thoughts on the subject.

[Lalatoot]

It is 12 hours for ERFA. If you feel you need more t4 then folks do add a levothyroxine dose to bring ft4 up.

[Buttercupsareyellow in reply to Lalatoot]

I’m on 50 levothyroxine and 60 (100 equivalent) of ERFA. That’s good to know. I normally take about 4am. Would you delay the day before’s dose to later in day so it falls 12 hours ahead of draw or take the dose from day of draw night before (but that would effectively mean you were double dosing the day before?)I am guessing then normal rules apply for the Levo bit, take after draw.

[Lalatoot in reply to Buttercupsareyellow]

Some folks on here split their normal dose the day before a blood test so the last of that days amount is 12 hours before.Personally I arrange my blood test to be 8 to 12 hours after my morning dose of t3. So I always do bloods at 2pm for consistency.

[pennyannie]

Hello Buttercupsareyellow :

I also take Natural Desiccated Thyroid :

The blood tests, ranges and guidelines were introduced to be used alongside synthetic thyroid hormones launched by Big Pharma in the middle of the last century.

With NDT you dose to the relief of symptoms and not a blood test :

With NDT results it's normal to see a low, suppressed TSH :

and likely a lower T4 reading than when on T4 monotherapy :

But your T3 should be higher in the range than when on T4 and the number to track :

I switched from 125 mcg T4 overnight to NDT and slowly built my dose up in 1/ grain increments over a period of around 6-8 weeks.

In this time my T4 - Levothyroxine lessened weekly as my NDT built up in my system.

I tested after being on 1+1/2 grains for 6 weeks and found my T3 and T4 numbers had almost swopped places from when I was on T4 monotherapy, as now my T3 is at around 90/110% through the range and my T4 at around 25/35% through the ranges, and I feel much better.

I wait around 10 /12 hours between last dose and blood draw :

No thyroid hormone replacement works effectively until your core strength vitamins and minerals, ferritin, folate, B12 and vitamin D are maintained at optimal levels.

If I had to present results to my local GP I'd likely wait 24 hours as she would be trying to fit my into the boxes, but likely still feel confused by my lower T4 and higher T3.

I'm with Graves Disease and following RAI thyroid ablation am managing lingering Graves, thyroid eye disease and hypothyroidism and self medicating :

[Buttercupsareyellow in reply to pennyannie]

Thank you. Really useful 😊

[pennyannie in reply to Buttercupsareyellow]

Just noticed I missed a 4 :

Have edited to read :-

I built up in 1/4 grain increments - you might like to buy a pill cutter ?

Your medication is referred to as Natural Desiccated Thyroid :

It was successfully used to treat hypothyroidism for over 100 years prior to Big Pharma launching synthetic thyroid hormone replacement.

NDT is made from pig thyroid dried and ground down into tablets, referred to as grains, with each grain containing all the same know hormones as that of the human gland namely, T1. T2, calcitonin plus a measure of T3 and a measure of T4 .

There are also synthetic T3/T4 combination thyroid hormone tablets in the the market place.