Took t3 in the am, should I take it at night again before a blood test?

[c115]

I took my T4&T3 this morning per usual but just remembered that I need to get my thyroid levels checked tomorrow morning. I know T3 levels are best checked within 24 hours but the lab doesn’t open until after the 24 hour mark.

Should I take my next daily dose of T3 tonight so that the levels are accurately recorded? Is it ok to take two doses in one day?

[SlowDragon Administrator]

In ideal world last dose of T3 should be 8-12 hours prior to blood test.

Could you reschedule test for Tuesday am? If not ....then your FT3 result will show false low

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and fasting. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Last Levothyroxine dose should be 24 hours prior to test, (taking delayed dose immediately after blood draw).

If/when also on T3, make sure to take last dose 8-12 hours prior to test, even if this means adjusting time or splitting of dose day before test

[c115 in reply to SlowDragon]

I understand. But if I took T3 this morning (like I usually do), can I take another daily dose at night so it is within the 12 hour testing window? So it would be two doses in a 24 hour period but would be within 12 hours of the lab draw?

I always skip my T4 before a test.

[SlowDragon Administrator in reply to c115]

Probably better to have slightly low result from taking dose too long before blood test....rather than taking tomorrow's dose early and then result might be too high

[c115 in reply to SlowDragon]

Thank you, I think you're right.