Hi I am a newbie and found the information so far very helpful!
I am due to speak to my GP tomorrow re blood results . I took 100 mgs at 7am had blood taken 13:30 . Having read here about getting blood done pref before 9am I am wondering how accurate my results will be
If I’m honest I’ve never taken any notice to my results before but the last few months I have felt awful! No energy , perm tired and no motivation and it’s making me feel quotes down/depressed I desperately need to take some control!
Thanks for any advice
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The results won’t be inaccurate as such as the results won’t be falsely skewed but the TSH naturally lowers and rises throughout day. Eating will also lower it.
A test taken a few hours after taking your dose will show higher FT4 than the rest of the day.
This can lead the GP who looks mostly at TSH to assume you are adequately medicated or even over medicated when the picture may be different if test taken as advised.
The difference may only be slight in some but if it’s the difference between being in range and flagging at abnormal level then it becomes relevant.
It’s also good to test in a consistent manner at it makes tracking of results easier to compare.
Come back with new post once you get recent and historic results
In future always book early morning test
Always get actual results and ranges on all blood tests
The best way to get access to current and historic blood test results is to register for online access to your medical record and blood test results
UK GP practices are supposed to offer everyone online access for blood test results. Ring and ask if this is available and apply to do so if possible, if it is you may need "enhanced access" to see blood results.
Having the blood taken around midday will give a lower TSH than if taken around 9am as can be seen in this graph d3i71xaburhd42.cloudfront.n... . It would be fair to point this out to your GP as usually the blood is taken in the morning when determining reference intervals.
Taking your levothyroxine about four hours before the blood will have negligible effect on TSH with a very small effect on fT4 as can be seen in these graphs karger.com/WebMaterial/Show... .
The only other influence on TSH is time of the menstrual cycle which can have a large effect on TSH as seen in the bottom two graphs here frontiersin.org/files/Artic... .
I had blood test done in November GP just said they were high and she wanted them retested. I didn’t question anything because I’ve always felt ok . I am a bit more with it now ,
I have been on 100 mcg levo for about 15years and have just had annual blood check never had any probs . It’s prob been last 12 months that I have started to feel tired/ache muscle and joints my GP has started looking at thyroid meds . She upped dose to 125 but said that was too high and put back to 100 ( I was not taking on empty stomach and having caffeine) so thought this was why ?
I have list of questions for GP tomorrow and will ask about previous tests . I only found out about optimum. Levels from info on here
Tell your GP that you've been reading up about your condition and have found Thyroid UK very helpful - and that you would be grateful if the next blood test could please include ALL the tests they recommend - ie TSH, free T4, free T3, antibodies (unless you know these have been tested and found to be high before) AND key nutrients - ferritin, folate, vit D and B12. My GP was very obliging when I asked nicely and mentioned Thyroid UK
Thanks for the advice I have planned to tell him I have looked at Thyroid UK ! I am normally quite good with looking into things this just passed me by !
It’s prob been last 12 months that I have started to feel tired/ache muscle and joints my GP has started looking at thyroid meds
She upped dose to 125 but said that was too high and put back to 100 ( I was not taking on empty stomach and having caffeine) so thought this was why ?
Aching joints frequently low vitamin D, extremely common on levothyroxine, especially if you have autoimmune thyroid disease
Sounds like your 100mcg daily is perhaps too low
Many people need to fine tune dose …..112.5mcg daily (cutting 25mcg tablet in half) …..or might need 125mcg 3 x week and 112.5mcg 4 days week…..or any slight dose adjustment
Levothyroxine is an extremely fussy hormone and should always be taken on an empty stomach and then nothing apart from water for at least an hour after
Many people take Levothyroxine soon after waking, but it may be more convenient and perhaps more effective taken at bedtime
No other medication or supplements at same as Levothyroxine, leave at least 2 hour gap.
Some like iron, calcium, magnesium, HRT, omeprazole or vitamin D should be four hours away
(Time gap doesn't apply to Vitamin D mouth spray)
If you normally take levothyroxine at bedtime/in night ...adjust timings as follows prior to blood test
If testing Monday morning, delay Saturday evening dose levothyroxine until Sunday morning. Delay Sunday evening dose levothyroxine until after blood test on Monday morning. Take Monday evening dose levothyroxine as per normal
REMEMBER.....very important....stop taking any supplements that contain biotin a week before ALL BLOOD TESTS as biotin can falsely affect test results - eg vitamin B complex
Which brand of levothyroxine are you currently taking
Many people find different brands are not interchangeable, Teva brand especially upsets many people
“According to the current TSH reference interval, hypothyroidism was not diagnosed in about 50% of the cases in the afternoon.”
“Further analysis demonstrated inadequate compensation of hypothyroidism, which was defined in 45.5% of the morning samples and in 9% of the afternoon samples”
If delaying taking levothyroxine until after blood test, you likely want to not eat or drink anything apart from water before taking levothyroxine and take levothyroxine immediately after blood test
It may (or may not) make a difference to TSH if fasting ….opinions differ
For optimal absorption you should take your levothyroxine on an empty stomach and away from coffee. I take mine just before breakfast (porridge or cereals and grapes) and have no problem. If you've been taking your levothyroxine close to breakfast it's OK to carry on doing so (without coffee) provided you are consistent, your dose will be adjusted to compensate for any minor loss of absorption. On the other hand you could take the tablets at night if you want a morning coffee.
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