Blood test

[Warrior75]

Hi 👋 I haven’t been on for a while. I’ve always had bloods taken first thing in the morning before taking my levo and in an empty stomach just wondering if this is still recommend?

In my area I could always go to my local hospital as a walk in to have bloods taken so I could get there for first thing ,they have recently stopped this and we have to have them done at the dr surgery. The dr has requested for me in to have TFT this afternoon and the next available appointment is the 9th July at 2.20 😢 I’m not in a position to get them done privately I think my levo needs increasing if I have them done at that time I’ve got no chance.

[shaws Administrator]

See if this would work in your favour. Keep in mind I'm not medically qualified.

Why not change from taking your a.m. dose to bedtime dose. i.e. levothyroxine at bedtime, then when a blood test is due you can miss night dose and take after blood test and night dose as usual.

endocrineweb.com/

A once-a-week dose can also be taken :-

"SUMMARY OF THE STUDY

A total of 23 patients in the United Kingdom were identified who had an elevated serum TSH despite seemingly adequate daily doses of L-T4 and no evidence of interfering drugs or diseases. Patients had baseline measurements of FT4 and TSH; then each patient received an oral weekly dose of L-T4 with periodic blood draws after the dose. They continued on the same weekly dose of L-T4 given under supervision for 4 weeks with serum TSH measurement 1 week after the final dose.

The average TSH before the study was 41 mU/L. In 19 of the 23 patients, the maximal rise in serum FT4 occurred by 120 minutes after taking the L-T4, with almost a doubling of FT4 at this time. The 3 patients with the most severe hypothyroidism had the lowest rise in FT4 at 120 minutes. At the final blood test after 4 weeks of treatment, TSH was reduced in 17 of 23 patients. In 6 patients, the 4-week TSH was higher than the baseline.

endocrineweb.com/

[greygoose in reply to shaws]

Changing the time you take your levo would not affect the TSH. And it's the TSH most doctors look at. TSH is highest early in the morning, and drops throughout the day and after eating. So, at 2.20 it would be pretty low. I don't think there's anything you can do to rig that. I'm pretty sure they do it on purpose so as not to have to increase the dose!

[shaws Administrator in reply to greygoose]

Thanks greygoose.

[greygoose in reply to shaws]

You're welcome.

[suztango]

Can you ask for a fasting blood test? That way you can get an early appointment. At 2:20pm, I think you’ll get a false negative result.

[Warrior75 in reply to suztango]

They won’t give me one as they don’t think I need to have a fasting blood test my hands are tied

[greygoose in reply to suztango]

You won't get a 'false negative' result, whatever you mean by that. You will get the levels of the hormones as they are at that time of day. Unfortunately, because the TSH will be lower than at 9.0 am, you probably won't get a result that will persuade the doctor that you need an increase in dose.

[suztango in reply to greygoose]

That’s exactly what I mean by false negative. The results won’t reflect the true need. Therefore it’s a false negative (likely to not want to do anything).

[greygoose in reply to suztango]

No, I don't follow that at all. Sorry. The actual problem is that the tests aren't fit for purpose, not that they give false results. So, we try to get round that by having the blood draw as early in the morning as possible.

[suztango in reply to greygoose]

Yes exactly The TSH is higher early in the morning. Therefore, having the test in the afternoon will (or could) give a false negative result. E.g. for someone who is only just outside the ‘normal range’ (I know the ranges are rubbish in the U.K.), if they have a blood test in the afternoon, they would be considered ok. But if they had the blood test early morning the hypothyroidism would be caught. The test in the afternoon is therefore a false negative result.

[greygoose in reply to suztango]

No. There is nothing false or negative about it. The test will give the correct level of TSH for that time of day. Negative doesn't come into it. Your terminology is completely wrong. And, if you said that to a doctor, he would probably laugh at you.

I'm not sure how you would get a 'false' TSH. But, you would get a false high FT3 if you took your T3 an hour or so before the test, or a false low, if you left it off for 24 hours. But, a false TSH? I don't see how that can be done.

[suztango in reply to greygoose]

False negative is different to false

I don’t think we are getting anywhere from this discussion so I’ll sign off now. I hope all goes well with you.