T3 dose timing before blood test

[Girtonian]

Hi all, looking for advice/reassurance. I have a blood test booked tomorrow at 8.30 am to check free T3 along with T4 and TSH - usual thyroid panel. My current dose is 50 mcg T4 taken early morning on waking and 15 mcg T3 taken in 3 doses: on waking (6-ish), 11.30 am and 4.00 pm.

I will delay the on waking doses tomorrow until after the blood test.

My question is, when to take my last dose of T3 today? I believe advice is 12 hours before the blood test? I think last time I split my afternoon dose into two and took half twelve hours before, which would mean 8.30 pm. ( Last time I was taking 75 mcg T4 and 10 mcg T3 in 2 doses).

I’m cutting up 20mcg Thybon Henning tablets, so the dosing isn’t very precise despite my best efforts to achieve equal quarters. It’s even harder to cut a quarter in half! I want to make sure my blood test gives a good snapshot of thyroid levels. I find I brighten up and can think and do things when the T3 kicks in, a couple of hours after the dose, but I’m still getting a massive dip about 4 in the afternoon.

Before I tried T3 I was on 100mcg T4 daily. I had the genetic test that showed I don’t convert T4 to T3 very well (1 of the 2 genes inherited from my parents predicted for this) . I see a private endocrinologist, John Wass, since about 18 months ago.

Thanks everyone, I know it’s a bit late to ask as the blood test is tomorrow, but I’ll be interested to know your thoughts - even if after the event.

[sparkly]

I would say you just need to take your 4pm dose about 8pm.

[Girtonian in reply to sparkly]

thanks! In the end I decided to spread the doses fairly evenly and took them at approximately 7.30, 2pm and 8pm.