When to take T3?

[Spangle15]

Hi. I have a blood test tomorrow at 10.40 am (the earliest I could get). What time is the earliest I can take my final T3 dose today? And should I fast? Thank you.

[fuchsia-pink]

Best to fast - if you can manage it and take your T3 meds 8 - 12 hours before the test so between 10.40 pm tonight and 2.40 am - this should give a good representative level of T3

[Spangle15 in reply to fuchsia-pink]

Thank you so much.

[SeasideSusie Remembering]

Spangle15

Fasting is only necessary if the TSH result is important, that is if we are looking to increase our dose or avoid a reduction then we need the highest possible TSH.

You are taking T3, your TSH is very likely very low or even suppressed anyway, so fasting isn't going to make any difference.

As fuschia-pink says, last dose of T3 should be 8-12 hours before your test. I'm doing a test tomorrow, hopefully around 8.30am, my last dose of T3 will be changed from my normal 5pm today to somewhere between 8.30pm and bedtime tonight.

[Spangle15 in reply to SeasideSusie]

Thank you Susie. The TSH doesn’t really matter as you say because it is always suppressed. They are also testing the following: Oestradiol, testosterone, SHBG, FBC, U+E LFT, Vit d, bone profile, TFT, ferritin, B12, folate, HbA1c and glucose, lipid profile, FSH and progesterone, Free T4, T3 and parathyroid level

And I’ve no idea if I need to fast for any of them so it might be better just in case.

[SeasideSusie Remembering in reply to Spangle15]

And I’ve no idea if I need to fast for any of them so it might be better just in case.

That's what I always do, they don't always tell you when you need to fast. You should for HbA1C and iron tests.

[Spangle15 in reply to SeasideSusie]

Thanks Susie.

[Surgebinder]

Is there different rules to T3 ?

For levothyroxine which is T4 if im not mistaken, i thought the general consensus is to not take it 24 hours before test.

I have my blood test tomorrow as wel, yippee !