NDT and blood tests

[Guest guest]

I'm due a blood test soon. I've done blood tests whilst on NDT and I don't take

any for the whole day beforehand. My current dosing schedule is 1 x grain 9am

1 x grain noon 1 x grain 4pm 1 x grain 8pm. So I normally take nothing the day

prior and book the blood test for morning 9am/10am and then resume my normal

schedule immediatley after the test is done. Am I doing this right please?

Recently, I had an 'on the spot' test done when I was at an appointment. I

didn't expect them to ask for blood - so I had taken my tablets normally. Those

blood tests freaked my GP when she got wind of it!!! Can anyone please explain

the reason for not taking the tablets prior - isn't that just giving a false

reading of what is actually going on? Thanks for any help.

[Guest guest]

Hi 'willowellies'

The reason we recommend not taking thyroid medication the

morning you have your blood drawn for thyroid function tests is because in

nearly every case, a doctor will " freak out " and believe you are

taking too much and becoming hyPERthyroid and want to lower your dose, or put

you back onto thyroxine only. Never, never allow a doctor to do this. If

necessary, explain to him/her that TSH will ALWAYS be suppressed in those taking

either synthetic T3 or natural thyroid extract. The pituitary only secretes thyroid

stimulating hormone (TSH) because it recognises when there is too little

thyroid hormone in the blood, so TSH is secreted to tell the thyroid gland to

start pumping out more and therefore, the TSH will be raised. However, when the

pituitary recognises there is sufficient thyroid hormone in the blood (as it

does for those taking T3 in any form) there is no need to secrete any TSH, so

the TSH result remains suppressed. However, T3 has a very short half life, and

it peaks in the blood 2 to 3 hours after taking it and having your fT3 measured

after taking it would mean the free T3 would be right at the top of the

reference range, or even above the reference range and the free T4 level is

often quite low in the range. This is quite normal. After a few hours, the T3

level drops, and this is the reason why we recommend our members to split their

dose of T3 (or NDT) because for some of us, after 6 to 8 hours, the good effect

starts to wear off, and we can feel a 'slump' around 3.00p.m. so need to take

another dose to 'keep the engine topped up'.

As your GP 'freaked out', ask her to do another thyroid function

test after you have not taken any thyroid hormone replacement that morning to

prove your point - she will see the difference. Likely that the fT3 will have

dropped by half, but the TSH is likely to be exactly the same, suppressed,

because there is absolutely no need for any TSH.

The day before you have blood drawn, I would stop the 4.00p.m.

and 8.00p.m. dose and take your tablets immediately after the blood draw.

Luv - Sheila

I'm due a blood test soon. I've done blood

tests whilst on NDT and I don't take any for the whole day beforehand. My

current dosing schedule is 1 x grain 9am 1 x grain noon 1 x grain 4pm 1 x grain

8pm. So I normally take nothing the day prior and book the blood test for

morning 9am/10am and then resume my normal schedule immediatley after the test

is done. Am I doing this right please? Recently, I had an 'on the spot' test

done when I was at an appointment. I didn't expect them to ask for blood - so I

had taken my tablets normally. Those blood tests freaked my GP when she got

wind of it!!! Can anyone please explain the reason for not taking the tablets

prior - isn't that just giving a false reading of what is actually going on?

Thanks for any help.