phlebotomist today asked.....

[App1]

I had a blood test today and was asked what time I had taken my last dose of Levothyroxine! This was for noting on the form. This is a first for me. Thought this might be of interest as I’ve had numerous tests since diagnosis early last year and have never been asked this.

[helvella Administrator]

It is interesting.

You are not quite the first - but it certainly doesn't seem common.

One problem is that there is no satisfactory way of making allowance for the time interval - for example, if it is two, four or eight hours. But still better that there is some awareness than that it is dismissed.

[raglansleeve in reply to helvella]

Unless they start using that piece of information against us. They may have a theory about timing that doesn't agree with the wisdom of the group here.

[tattybogle in reply to raglansleeve]

personally i suspect that they read the internet too , and have twigged that some patients will leave a much longer gap to get a lower fT4 result ( and may therefore be trying to get a higher TSH~ even though that wouldn't usually work ).....and so they are asking the direct question to put us on the spot about it .

i'd like to think they are asking for a 'better' reason than just to try to catch people who are trying to fiddle the test , but .. whatever the reason .. collecting this information about time of last dose is a definite step forward as far as i'm concerned .. i'm very glad someone has starting to do it.

The protocol of recording 'time of last dose' should be adopted everywhere .. (as should taking thyroid tests at same time of day)

[Carri3]

In Australia I was asked at every thyroid blood test.

[JoVH in reply to Carri3]

I’m in Newcastle NSW and have always been asked and had it noted.

[Summer64]

I've never been asked that and do wonder if it makes a difference if you have your blood tested at different times each time.

[tattybogle in reply to Summer64]

yes it will, the difference will not be massive , but there will be a difference.

TSH will change a little (in some people) accord into time of day ,, and ft4 will change (in everyone) according to how long since the last dose of Levo was taken.

See this 'pinned' post (in the replies there are a couple of graphs which show the difference time of last dose makes to fT4 result) : healthunlocked.com/thyroidu... suggested-thyroid-hormone-test-timing-protocols

[Noelnoel in reply to tattybogle]

Last week I got my MMH test boxes muddled and ended up taking the TFT at 11am and two hours after my Metavive. FT3 was 10.4 (3.1 - 6.8) and FT4 at 30%, which was only slightly higher than last time and as would be expected and is always the case, TSH was way under

[tattybogle in reply to Noelnoel]

at 2 hrs it's tricky to be certain whether the T4 /T3 has had enough time to be absorbed from the gut and show up in blood .. to some extent it probably depends on the individuals speed of digestion, eg. someone with really slow digestion might not show the peak level until 3 hrs , but someone with really fast digestion might show the peak after just an hour.

Time of dose shouldn't have a significant effect on TSH though .. the TSH level has largely been decided already .. most TSH is secreted in through the night time ,,,,so you'll be getting 'whatever' TSH result you get , based largely on the previous nights TSH output .

[Noelnoel in reply to tattybogle]

Well whichever way, the test has been a waste of time, money and blood! Takes me an age to get a few measly drops into the vial. I think I must have quite quick digestion though for FT3 to be at 10.4 2hrs after ingestion of Metavive because on that dose it usually reads around 5.8

[Me2U]

I've never been asked that - as of yet. Got a test in June so will see if anything changes. I will say that I never get offered an early morning appointment always seems mid-day,even though I ask if there's nothing earlier!

[Gillybean1]

Hi App1,

I now like to get ahead and when sent unexpectedly to A&E (chest pain) a few years back, when they took a heap of bloods I said straight away "please note ive just taken an afternoon dose of NDT which will be peaking right now if your wondering why T3 may be v high in range". Dr said he was glad I mentioned it as he would have queried it, and so disregarded 'upped' result.That said he was quite young and he did seem to be well informed on thyroid stuff/different meds, more than most..........so there is hope!!

Now whenever I submit copies of test ive done to GP or onto Endo pre follow up, I write all over them, last meds taken, off biotin, that T3 suppresses TSH (latter one for the GP).

I know it sounds arrogant, but im just so tired of standing up for myself, explaining evey time, the fight for my health. So this saves my limited energy......

Every best wish, G