Correct way of doing a thyroid blood test if you take liothyronine

[Hafsah2345]

Hi all

I was writing to ask about whether anyone knows what the correct way to do a thyroid blood test is if you take liothyronine. I am currently on levothyroxine 100mcg/75mcg alternate and 5mcg lio twice a day (once with my levo in the morning at 8am, and once at 5.30pm).

I usually do my blood tests also at 8am and do not take any thyroid meds before hand (or after my 5.30 dose from the previous day obviously)however on my medichecks thyroid test guide and according to my endo you should be taking your first dose of lio an hour before your test? Does anyone know what the correct answer is because I’m worried my test results are probably incorrect. Many thanks!

Kind regards,

Hafzah

[SeasideSusie Remembering]

Hafsah

If you take your lio (or your Levo) before the test then you will be measuring the hormone level as it approaches it's peak in the blood. This gives a false high level. If we want a measure of the normal circulating level then we take last dose of Levo 24 hours before the test and last dose of lio 8-12 hours before the test. This is what we always advise here, so we would suggest that you move your afternoon dose to the evening, between 8pm and midnight, the night before your test.

[Hafsah2345 in reply to SeasideSusie]

Hi susie

Thank you so much for the clarification, makes a lot more sense. Going forward shall move my later dose so that it’s about 8-12 hours before as opposed to 5.30 which would be too early

Kind regards,

Hafzah

[jimh111]

Definitely not have the blood taken within four hours of the last dose of T3, it will give a false result. I would be suspicious of any physician who suggests having the blood taken within a few hours of taking T3.

Ideally you would have the blood taken about half way between T3 doses, to give a rough idea of average fT3 levels. However, in your case this will be difficult and as you are taking only 5 mcg twice daily I would postpone your morning dose until after the blood draw, or better still bring the morning dose forward to the previous night just before bedtime. Five mcg of liothyronine will have little effect on your fT3 level.

[shaws]

I take T3 alone with one glass of water when I awake and wait an hour before I eat.

I have done so for several years and have been well.

I follow Dr John Lowe's method and he was a doctor, scientist, researcher and expert on the use of T3. He took T3 only too. He was also an Adviser to Thyroiduk.org.uk.

Unfortunately Dr Lowe had a bad fall that caused a bleed in his brain and it caused his death.

I always get the earliest appointment and it is a fasting test (I drink water) and do not take T3 until after the blood draw.. I've never had any query on my results.

Best of all I don't have symptoms and feel well.

web.archive.org/web/2010103...

[LindaC in reply to shaws]

💚 One of the Finest, shaws! 🍀