Confused about best time to take bloods on t3/t4 combo

[Daisybellerose]

Hi there

Just wondering if someone could clarify the best time to have blood taken when in T3/T4 combo. I’ve read first thing in the morning before medication, but some say wait 12/18 hours after last t3 dose (to see what in effect you are hanging on to) and others say don’t leave it more than 8 hours so the T3 is still in the system. I’m currently trying to get my t3 optimal but struggling to find consistent advice. Can anyone shed any further light on this? Thanks

[greygoose]

The best thing to do is leave a gap of 24 hours between last dose of levo, and 8 - 12 hours between last dose of T3 and the blood draw. 18 hours would be too long and give you a false low. T3 stays in the blood for about 24 hours, so if you leave 12 hours, that will be mid-cycle, and is said to be the best time to test.

[Daisybellerose in reply to greygoose]

Brilliant that makes sense thank you for the clarification

[greygoose in reply to Daisybellerose]

You're welcome.

[SeasideSusie Remembering]

If you normally take your T3 in one dose, split the dose the day before and take the first half in the morning and the second half 8-12 hours before your blood draw appointment.

[Daisybellerose in reply to SeasideSusie]

Thank you 😊 x