Blood tests while on NDT

[Alex_p]

Hello,

When doing blood tests while on NDT, when is the best time to do them? And when should the last dose of NDT should be the previous day?

For reference, I take half a dose at 4 AM and half at 12 PM. I have the blood test scheduled at my GP at 8:15 AM.

[waveylines]

I leave a 24hrs gap between my NDT and blood test. The T3 in NDT has a much more gradual uptake and drop then Liothyronine. My three knowledgeable thyroid doctors all advised me to test like this. So I'd take your midday dose at breakfast time, don't take the later dose and test the following morning. ( It's up to you whether you want to take your combined daily dose at breakfast the day before your test.)Hope that makes sense!!

[Delgor in reply to waveylines]

Well I'm really glad to hear you say this waveylines as I have always left 24 hours between supplementing and testing but was then told by the hospital endo and the private endo (whom I only had two zoom meetings with) that it should be split the day before so as to only leave 12 hours before testing and was led to believe that I had been overmedicating for years😕

[waveylines in reply to Delgor]

Hmmm that's because they are going on the uptake drop of Liothyronine which is much faster. Maybe they were not familiar with the slower uptake of NDT? Sadly fewer and fewer are.... Lol xx

[Delgor in reply to waveylines]

I won't say too much but suffice to say that I didn't think much of either of them😐

[pennyannie]

Hello Alex P :

Which ever way round you go - your blood test on NDT will not look like any other thyroid blood test.

When optimally medicated your TSH will be low suppressed :

Your T4 proportionately likely lower in the range BUT your T3 proportionately higher in the range than when taking synthetic thyroid hormone replacement.

It's suggested that NDT peaks in the blood at around 10/12 hours after last dose - and we use the ranges as a guide - as there are no ranges or guidelines for NDT and you treat to the relief of symptoms.

Consistency is more important than anything else so you can actually track any shifts in results.

Are you supplementing any vitamins and minerals and stopped all around a week before ?

Is your doctor aware of your treatment option and supportive ?

Is this your first blood test, and you have been on this current dose for 6-8 weeks ?

Have you noticed some relief of symptoms of hypothyroidism ?

[Alex_p in reply to pennyannie]

This is a test requested by my GP in order to ‘continue providing prescriptions’. I don’t know if they know I’m taking NDT, or even care, they prescribe levothyroxine. I have told my NHS endo that I do, and he might have sent a letter to the GP. I’m taking part of the prescribed levothyroxine so I would need them to continue prescribing. They also prescribe calcium and that I’m taking. I’ve stopped the vitamin B complex. I do feel better on NDT but I’ve only added 25 mcg levothyroxine about 3 weeks ago, which is already starting to help with hair falling out.

[pennyannie in reply to Alex_p]

So you have added back in 25 mcg T4 3 weeks ago because of hair loss - you need to wait 6-8 weeks from this addition of Levothyroxine to get an accurate picture of your bloods.

So you are now taking 1 grain NDT + 25mcg T4 at 4 AM and 1 grain NDT at noon and stopped all supplements, especially those containing biotin a week ago;

I think I'd fast o/night and take the NDT and T4 - after the blood draw.

[Alex_p in reply to pennyannie]

When should I take the last dose the day before the blood tests? Should I take the full dose in the morning? And not take anything for 24 hours? I’m not really interested in these results, just to not get very high values of FT4 and FT3. Although last time I tested them, FT3 was middle of range and FT4 was close to the bottom value. And I had taken the NDT the day before like I usually do.

[pennyannie in reply to Alex_p]

I would continue with the timing of the blood test as usual - unless the endo requesting the tests states different.

Presumably they are being run to compare to previous readings so maintaining same timing etc is of importance.