I'm having a blood test tomorrow morning at 9am for thyroid. The doctor refuses to test anything but TSH, T3 and T4, saying the usual that if TSH is within range, the other results will be ok too! I've never had any thyroid problems since I started talking levothyroxine 11 years ago. I have never been asked to fast at all.
He doesn't want me to fast as he says it is not necessary.
My last levothyroxine was taken at 7.30 am this morning, so if I don't take it at my usual time of 7.30 tomorrow, it will be over 25 hours since my last one by the time the blood is taken at 9 am tomorrow. Or shall I get up early and take it 2 hours before the test? I've been in a quandary what to do, and do I fast as well?
What difference does it make to results if I take it at 7am tomorrow or not take levothyroxine for over 25 hours. It's all so confusing.
I suppose all I can do, is do what he says, don't fast, take the tablet,75 mcg, then try a private test. The reason for maybe trying private is that I generally feel unwell, heart palpitations, maybe it's just the heart meds after my heart attack last December?
Lily
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MrsSuzuki
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Doctors aren’t taught that TSH starts higher in the day and goes down so they don’t advise it’s necessary.
They also believe if TSH is in range so is FT4 & FT3 but that’s false too.
It might not be required to fast but there’s nothing to stop you from choosing to. Did your doctor instruct you to eat breakfast?
Usually it’s recommended to delay dose until after draw or it may show a false high (FT4) . So you’d only be delaying by a few hours.
Again doctors don’t think it matter & the TSH may only change slightly but if it’s the difference between being in range (& not having FT4 tested) and just outside the range then it becomes relevant.
The other reason it’s recommended to - test early, fast overnight & delay dose is that testing consistently mean comparisons can be made rather than seeing results vary due to testing under different conditions.
Remember biotin or b complex supplements containing it should be avoided before test as can interferes with testing process. Standard supplement doses a few day, high doses a week.
He doesn't want me to fast as he says it is not necessary.
So don't mention it.
My last levothyroxine was taken at 7.30 am this morning, so if I don't take it at my usual time of 7.30 tomorrow, it will be over 25 hours since my last one by the time the blood is taken at 9 am tomorrow. Or shall I get up early and take it 2 hours before the test?
What difference does it make to results if I take it at 7am tomorrow or not take levothyroxine for over 25 hours.
The extra one and a half hours isn't going to make much difference so don't take your Levo tomorrow before the test, take it after. If you take it before the test you will get a false high FT4 level. If you leave it off for too long, say 30 hours, you will get a false low FT4.
Always advised here:
* Book the first appointment of the morning, or with private tests at home no later than 9am. This is because TSH is highest early morning and lowers throughout the day.
In fact, 9am is the perfect time, see first graph here, it shows TSH is highest around midnight - 4am (when we can't get a blood draw), then lowers, next high is at 9am then lowers before it starts it's climb again about 9pm:
If we are looking for a diagnosis of hypothyroidism, or looking for an increase in dose or to avoid a reduction then we need TSH to be as high as possible.
* Nothing to eat or drink except water before the test - have your evening meal/supper as normal the night before but delay breakfast on the day of the test and drink water only until after the blood draw. Certain foods may lower TSH, caffeine containing drinks affect TSH.
* If taking thyroid hormone replacement, last dose of Levo should be 24 hours before blood draw, if taking NDT or T3 then last dose should be 8-12 hours before blood draw. Adjust timing the day before if necessary. This avoids measuring hormone levels at their peak after ingestion of hormone replacement. Take your thyroid meds after the blood draw. Taking your dose too close to the blood draw will give false high results, leaving any longer gap will give false low results.
* If you take Biotin or a B Complex containing Biotin (B7), leave this off for 7 days before any blood test. This is because if Biotin is used in the testing procedure it can give false results (most labs use biotin).
These are patient to patient tips which we don't discuss with phlebotomists or doctors.
Our heart can be affected if we have hypothyroidism as we need sufficient hormones in order to produce T3.
T3 (also called liothyronine) is the 'active thyroid hormone' and brain and heart have the most T3 receptor cells and without an optimum dose we will develop unpleasant symptoms.
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Need Advice Please 
Increased anxiety…
I’m fine. Really?
Thyroidectomy or not? Thyroidmegaly and multi modular goiter. 
methinks it's time to add some T3......thoughts ?
