Posted a few weeks back about my dad. He has been on an increased dose of levo for about 7 weeks now so is due his repeat TFT through his GP this week. They will only do TSH and T4.
They are testing for folic acid (he is on 5mg folic acid at the min) and serum b12 too (he had b12 injections last month so don't think the tests will be that useful). He had his ferritin checked a couple of weeks ago but docs refusing to do Vit D.
I am going to privately test through medichecks this wk also so we can get T3 and Vit D.
Regarding timing of test, his GP test is 9.20am. Previously he has tested in the afternoon etc so I was worried that if he goes for his test on empty stomach with no levo in the morning (as recommendedo on this board) that it will not be comparable to last test?
I had a read on the thyroid website and it didn't mention anything about testing on empty stomach without taking levo?
just looking for some clarification.
thanks all
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Needleandthread44
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When we do thyroid tests, if we are looking for an increase in dose or to avoid a reduction then we need TSH to be as high as possible. TSH is highest early morning and lowers throughout the day so a 9am blood draw will give a higher TSH than an afternoon blood draw. It's the best time to test to avoid a reduction if the GP is only dosing by TSH (which most do).
I was worried that if he goes for his test on empty stomach with no levo in the morning (as recommendedo on this board) that it will not be comparable to last test?
Certain foods and drink can affect TSH so it's really best to have water only before the test to get as accurate a result as possible.
The reason we leave 24 hours between last dose of Levo and the test is to avoid a false high or false low FT4. If we take Levo before the test we get a false high FT4 result which may prompt the GP to lower the dose.
Your father has had a dose increase, I can't see the point in comparing the new result with previous ones, he would be better starting afresh with his new results as a new base and having all tests no later than 9am in future and with correct time gap between last dose of Levo and blood draw.
They are testing for folic acid (he is on 5mg folic acid at the min) and serum b12 too (he had b12 injections last month so don't think the tests will be that useful).
There is no point testing B12 if he is having injections, the result is bound to come back high and some doctors use this as a reason for not continuing with the injections without realising this is supposed to be what they do.
Personally I would refuse the B12 test (we are entitled not to give consent to any medical procedure) citing the fact that having injections is intended to raise the level so what's the point as it will come back high.
If the test is done, don't let the GP cancel the injections because of a high result.
I am going to privately test through medichecks this wk also so we can get T3 and Vit D.
Only test on a Monday or Tuesday and send back to arrive next day. Don't rely on the Tracked24 return envelope to get the sample there the next day, it is not guaranteed and one member recently had her sample take 4 or 5 days to arrive. The only way to guarantee next day delivery is to go to the Post Office counter and pay extra for Royal Mail's Special Delivery Guaranteed Next Day by 1pm
Don't do the test during a heatwave, the blood may spoil in hot temperatures. Best to wait until temperatures are back to normal.
His TSH will be a little higher than if he has the blood taken in the afternoon (maybe 20% higher). I wouldn’t go on an empty stomach, it makes no difference apart from risking fainting when the blood is taken. fT4 will be about 10% higher one to five hours after taking your levothyroxine dose so leave at least five hours before taking the blood or factor this in. He could take the levothyroxine the night before instead of the following morning if convenient.
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Blood test 
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