Time to take thyroxine before test

[Cassandra]

Hi everyone

I usually take my thyroxine at 7am each morning - I am having a thyroid blood test at 9 am on Thursday morning. Before test should I take my last dose of thyroxine on Wednesday morning which would leave approximately 26 hours in between.

Many thanks to everyone.

[SlowDragon Administrator]

Yes that's correct (you could take Wednesday dose of Levothyroxine at 9am day before...then it's 24 hours)

Recommended on here that all thyroid blood tests should ideally be done as early as possible in morning and before eating or drinking anything other than water .

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

This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

Are you also still on T3? make sure to take last dose 8-12 hours prior to test, even if this means adjusting time and splitting of dose day before test

Obviously you need FT3 tested

Important to test vitamin D, folate, ferritin and B12 at least annually