Are we meant to take our Levothyroxine dose bef... - Thyroid UK

Thyroid UK

140,948 members166,084 posts

Are we meant to take our Levothyroxine dose before a blood test or wait until after bloods are drawn?

Charltonjl profile image
10 Replies

I've had conflicting advice so not sure whether it would have impacted my recent test results. Thank you

Written by
Charltonjl profile image
Charltonjl
To view profiles and participate in discussions please or .
Read more about...
10 Replies
SeasideSusie profile image
SeasideSusieRemembering

Charltonjl

Always advised here, when having thyroid tests:

* Blood draw no later than 9am. This is because TSH is highest early morning and lowers throughout the day. If looking for a diagnosis of hypothyroidism, an increase in dose of Levo or to avoid a reduction then we need the highest possible TSH

* Nothing to eat or drink except water before the blood draw. This is because eating can lower TSH and coffee can affect TSH.

* Last dose of Levo 24 hours before the test, take that day's dose after the blood draw. This is because if you take your Levo before the blood draw the test will measure the dose just taken and show a false high. If you leave longer than 24 hours the result will. Show a false low.

These are patient to patient tips which we don't discuss with phlebotomists or doctors.

Florals profile image
Florals in reply toSeasideSusie

Thank you. I have been wondering about this exact question myself so thank you SeasideSusie for clarifying so well.

Charltonjl profile image
Charltonjl in reply toSeasideSusie

Yes thank you so much ☺️

041051 profile image
041051

I take my thyroxine at night and I had a blood test at 10-00 the next morning. I had spoken to my G.P. a couple of days before because I had been having symptoms for some months. The result showed that I needed to increase my thyroxine.

greygoose profile image
greygoose in reply to041051

Well, imagine how low it would have been if you'd left the full 24 hours! Which you will need to do, once your FT4 gets higher, or you will find yourself with a reduction in dose. :)

041051 profile image
041051 in reply togreygoose

We all do things differently depending on our own situations.

greygoose profile image
greygoose in reply to041051

Fine, but it does mean we get different results. You could, just for once, on the day before the test, take your levo at a diffiferent time, no? Just saying that for your benefit, doesn't make any difference to me. But, I'm not sure it's a good idea to be recommending that method to other people. :)

041051 profile image
041051 in reply togreygoose

I wasn't recommending any method, I was just commenting on a post by recounting my experience. I had symptoms, I spoke to my G.P. , I had a blood test and my medication was altered. I have to speak to my G.P. if I show signs of the dosage being too high and have another blood test in 2 months.

Marz profile image
Marz

You can scroll down and down the page to Related Posts where you will find 10 more similar to yours ..🌻

Charltonjl profile image
Charltonjl

Thanks everyone 😊

Not what you're looking for?

You may also like...

Take levo before or after blood test?

Not sure if this is allowed but have been reading a post on the Facebook group Thyroid Group UK...

When to take the last T3 dose before a blood test.

Just asking for some clarity about the statement I hear often on this forum, to wait 8 to 12 hours...

Do I take my medication before blood test or not?

I'm in a dilemma I take all my thyroid medication first thing in the morning. I'm on 20mcg T3 and...
W3ndy2159 profile image

When to take T3 before blood test - advice please.

This week I'll be doing my next Medichecks blood test for TSH, T4 and T3. I do the blood tests at...
Tasker profile image

When to take second dose T3 prior to blood test?

I have a blood test to check levels next week. I take Levo in the morning around 6am along with 5...
Piglet1956 profile image

Moderation team

See all
SlowDragon profile image
SlowDragonAdministrator
helvella profile image
helvellaAdministrator
RedApple profile image
RedAppleAdministrator

Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.

Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.