NDT BLOOD TEST ADVICE PLEASE

[DubStar]

I have read a lot of posts on here about NDT and thyroid blood tests.I take 60mg ERFA which I take once a day at 6amMy plan was to do the test before taking my usual 6am dose as advice on here is to do this. However, I have also read on here that I should be splitting my dose the day before, half at the usual time and half at 6pm, 12 hours before my test.

If anyone can clear this up I would be very grateful.

Many thanks

[Hypopotamus]

I use NDT, and take my whole dose first thing in the mornings. On the day of the blood test, I don't take my NDT until after having the test. So when I have the blood taken, I have at least 24 hours since taking my thyroid medication.

[DubStar in reply to Hypopotamus]

Thanks very much for the reply 😊

[FallingInReverse]

Guidance is to split day before - see details here:

healthunlocked.com/thyroidu...

I misinterpreted guidance for t3 for a long time, and ended up missing an over range ft3, as you might too if you wait a full 24 hours.

[DubStar in reply to FallingInReverse]

Many thanks for your reply and the link 😊

[DubStar in reply to FallingInReverse]

I am still confused because one of the links says there's no need to split your NDT before a thyroid blood test and another says you should.I feel terrible if I split my ERFA, which I take 6am in one go (I experimented once).

Could I do 3/4 at 6am and 1/4 at 6pm?

[FallingInReverse in reply to DubStar]

Dubstar- I never did click through all the links!! I think you are right… but asking those who shared the original post/info.

radd helvella TSH110

OP has read pinned post on timing of last doses for bloodctest and one of the links to Radds post with great dialogue leads to a conclusion that with NDT it’s not about the splitting but the consistency.

Is that fair to say?

I have zero personal experience on NDT.

Can you guys weigh in on Dubstar’s question here based on the research you shared?

[helvella Administrator in reply to FallingInReverse]

I have no experience of taking desiccated thyroid.

An awful lot depends on what your prescriber thinks. If you do not have to convince them of anything, then the issue is much less significant.

It would be very interesting to see what results you got from being tested at, say, 08:00 after taking, 18:00 and 06:00 the next morning before taking. Of course, I know it won't happen!

[tattybogle in reply to helvella]

re. NDT ... i just came across this europepmc.org/article/med/4... (no abstract , but if you look in 'full text links' , there's an open access link that works )

Studies on the changes with time in the concentrations of serum triiodothyronine, thyroxine and thyrotropin after the oral administration of various thyroid hormones (author's transl)].

it's only moderately illuminating 'cos it's mostly in Japanese, and from 1979 , so i assume it's looking at total T3 / T4 , rather than fT3/fT4,,, but i does have some figures/ graphs for T3 level @3-5hrs compared to @18-24hrs after taking various doses of NDT.

[helvella Administrator in reply to tattybogle]

Interesting paper.

This is my attempt at explaining - as far as I understand!

helvella - Scheduling Blood Draws

Factors to consider when choosing time for blood draws. Includes links to several documents/webpages and previous HealthUnlocked posts.

Last updated 30/12/2024

Link to blog:

helvella.blogspot.com/p/hel...

[DubStar in reply to helvella]

Many thanks for your reply 😊

[DubStar in reply to tattybogle]

Many thanks for your reply and info 😊

[FallingInReverse in reply to tattybogle]

I’m going to have to read that… after 1 1/2 years of blood tests I did all but the last 2 with an 18 hour gap on half my daily dose or something dumb like that.. I have no idea what I was thinking.

My ft3 popped from near top to clearly over when I did it right with the 8-12 hour gap.

I’ll have to look at that paper and see if any similarities when I switched.

[tattybogle in reply to helvella]

and this one too .... also from the 1970's ( Bianco uses them as references for T3 peaks after NDT)..... haven't read it , not sure if this one relates to Free T3 or Total ,

pmc.ncbi.nlm.nih.gov/articl...

A New Radioimmunoassay for Plasma l-Triiodothyronine: Measurements in Thyroid Disease and in Patients Maintained on Hormonal Replacement

Martin I Surks , Alan R Schadlow , Jack H Oppenheimer

[DubStar in reply to helvella]

Thanks 😊 yes, if only we could get all the tests we really need! Luckily I don't have to convince my prescriber, so that decided me. Split doses make me feel terrible.

[DubStar in reply to FallingInReverse]

Many thanks for your reply 😊

[TSH110 in reply to DubStar]

I leave my one daily dose of NDT till after the test and do that every time to keep it the same each time but maybe the dose splitting has some merit before the test - I’d just do the same thing every time so the tests can be compared like for like. Probably dose splitting is the ideal, reading the data in the link given. Having not done it I can’t offer timings I’d have to check what’s advised.

[DubStar in reply to TSH110]

Many thanks for your reply. As splitting my dose makes me feel awful, I decided to leave 24 hours. As you say, if I do this every time it should be OK!

[TSH110 in reply to DubStar]

Also if you feel ok it ought to be ok

I did split my NDT dose initially but never had a blood test whilst doing so. I found one daily dose was no different t to two and a lot less hassle