Thyroxine blood test

[manxonia]

I am due a blood test for thyroxine levels,is it best to not take throxine until after test?

[Bambamg]

I started thy 1995 always ate and took tablets. Only now last year or so i have to fast ( water only for 12 hours. ) take meds at 6am. Blods 9am. I would phone and confirm.

[SlowDragon Administrator in reply to Bambamg]

Don't ask about timing, most medics deny its important

[Neverending63]

You are right take meds after blood test and get test done as early as possible in the morning. Also best to be fasting. Doctors won’t tell you any of this info though. It’s patient to patient advice. It then gives the best results otherwise all you are testing is the meds in your system.

[manxonia in reply to Neverending63]

I was told to take as usual!!!

[SlowDragon Administrator]

All thyroid blood tests should ideally be done as early as possible in morning and fasting. Do not take Levothyroxine dose in the 24 hours prior to test, delay and take 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)

For full Thyroid evaluation you need TSH, FT4 and FT3 plus both TPO and TG thyroid antibodies tested. Also extremely important to test vitamin D, folate, ferritin and B12

Low vitamin levels are extremely common, especially if Thyroid antibodies are raised

[manxonia]

I was told by a chemist pharmasist that it doesn't matter!!