Blood rest take levo before bed

[Purplebum]

I have blood test on Friday at 9am but unsure what best to do re taking levothyroxine as I take before bed and the recommendation here say last meds 24hrs before test. All suggestions greatly appreciated x

[SeasideSusie Remembering]

Purplebum

You change the time of taking your Levo for a couple of days before the test so that you get the advised 24 hours time gap between last dose and test.

So you are having your test at 9am on Friday - you should do the following

Wednesday night - delay your dose until 9am on Thursday morning

Thursday night - do not take dose

Friday morning after the blood test - take Thursday night's dose

Friday night - take dose as normal

[jimh111]

We store about 10 days' worth of levothyroxine in our blood so one days' dose will have very little effect on fT4 or TSH levels.

This graph link.springer.com/chapter/1... shows the effect on (total) T4 of a single 600 mcg dose of L-T4. You can see that TT4 jumps to around 102 after three hours and drops to 90 after 24 hours. A typical dose will likely have a much smaller effect. I would simply avoid having the blood taken within a few hours of taking my levo. but I don't see any advantage in having a larger gap. Taking your levo at bedtime with a morning blood take is ideal as you will be measuring average fT4 and TSH levels although the daily variation caused by the levo will be tiny.

This does not apply to T3 medication as T3 has a short half-life.

[tattybogle]

There is a peak in blood levels of T4 from absorption of levo starting (approx) 2 hours after taking the tablet... and lasting to (approx) 6 hours after taking the tablet . On the graph i've seen ( which i can't find , sorry ) by the time you get to 12 hours after taking it , this peak has fallen to very nearly the same level it would be after 24 hours .

The bit you really want to avoid is that peak that happens between 2-6 ish hours after taking the tablet .

And the next most important thing is to find a convenient method you can do every time so all your tests are done in the same way: same gap from last dose / same time of day for test ..... so that you can always compare the results properly with the previous test .

So personally for convenience and consistency i would take the evening levo at 9pm , then always have blood tests at about 9 am .

and just take into account when interpreting your results , that the fT4 result taken after 12 hours might be very slightly higher than it would have been if you'd left a 24 hour gap .. but in my opinion , a 12 hour gap means this difference would be negligible.

[Purplebum]

Thank you for your replies.

[SlowDragon Administrator]

please write a new post with your most recent thyroid and vitamin results

TSH, Ft4 and FT3

Vitamin D, folate, ferritin and B12

Plus information on what dose and brand of Levothyroxine you’re currently taking

And what vitamins

[Purplebum in reply to SlowDragon]

Last year the only bloods were for TSH 0.8 range 0.27 - 4.20. This was NHS. I'm hoping to do private tests soon and based on what that looks like and my current meds and supplements look into trying to include T3 buying privately. I'm currently taking 100mcg and 75mcg alternate days. I had to fight to get increase from 75mcg.

[SlowDragon Administrator in reply to Purplebum]

Before considering starting T3 important to test to see where Ft4 and Ft3 are

And check all vitamins are optimal

Test early morning, ideally before 9am and last dose levothyroxine 24 hours before test

Only drink water between waking and testing

Stop vitamin B complex 5-7 days before test

If taking iron supplements stop this week before test too

[Purplebum in reply to SlowDragon]

Thank you for your recommendations I will definitely bear them in mind.

[SlowDragon Administrator in reply to Purplebum]

Also worth trying strictly gluten free diet and few months later dairy free too