Time of Day Does Matter For TSH

Time of Day Does Matter For TSH

It sometimes feels like you are banging your head against a wall.

You believe something, you repeat it, and repeat it, and repeat it.................................

Then you start to have a moment of self-doubt. Surely, if that thing is true, the whole world would already have woken up and taken it into account? Perhaps I am wrong...

Eventually you see a paper, a real clinical research paper, which revives your belief. So you want to shout it from the rooftops. Again.

This is such a paper. :-)

The take-home message is:

If you want your TSH test to get you diagnosed hypothyroid, get the blood drawn in the morning, as early as possible.

In my view, now that TSH reference ranges are somewhat more sensible than they were, say, ten years ago, this variation through the day has increased in importance.

And, of course, the same basic argument applies when TSH is used to monitor treatment.

Endocr Res. 2013;38(1):24-31. doi: 10.3109/07435800.2012.710696. Epub 2012 Aug 2.

Clinical significance of TSH circadian variability in patients with hypothyroidism.

Sviridonova MA, Fadeyev VV, Sych YP, Melnichenko GA.

Source

Federal Endocrinological Research Centre, Moscow, Russia. maska119@rambler.ru

Abstract

OBJECTIVE:

To investigate the clinical significance of thyroid-stimulating hormone (TSH) circadian variability in patients with hypothyroidism.

DESIGN:

A total of 20 women with subclinical hypothyroidism and 22 patients taking L-thyroxine replacement therapy for hypothyroidism were enrolled in the study. Measurements of serum TSH levels were done twice a day from 08.00 to 09.00 a.m. and from 2.00 to 4.00 p.m.

RESULTS:

The morning median TSH value in the patients with subclinical hypothyroidism was 5.83 mU/L; in the afternoon, it was 3.79 mU/L. The range of TSH circadian variability reached the level of 73%. According to the current TSH reference interval, hypothyroidism was not diagnosed in about 50% of the cases in the afternoon. The morning median TSH value in the patients taking l-thyroxine was 3.27 mU/L; it decreased to the value of 2.18 mU/L in the afternoon. The range of TSH circadian variability reached the level of 64.7%. Further analysis demonstrated inadequate compensation of hypothyroidism, which was defined in 45.5% of the morning samples and in 9% of the afternoon samples (p < 0.05).

CONCLUSION:

The time of blood sampling has an important role in the interpretation of TSH levels. Moreover, the high TSH circadian variability should be considered in discussions about the narrowing of its reference range.

PMID: 22857384 [PubMed - in process]

ncbi.nlm.nih.gov/pubmed/228...

Rod

Alarm clock - maybe a bit too early to find someone to draw your blood?

18 Replies

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  • My local hospital lab opens for blood tests at 8am, but you have to be there well before that to get to the front of the queue!!

    The last time my bloods were done, I was at my GP's surgery for when they opened at 8.30am for there to be 7 infront for testing, so it was 9.20am before I got called in.

    Would being up and about for a couple of hours before testing make a difference??

    If not, I will make sure I take a book and go and wait for the lab to open next time!!

    Ann xx

  • I'd like to refer back to some documents before answering - but at least it is being done in the morning and not the afternoon!

  • It makes you wonder how long it will take before this filters down to the practice level. One of the studies Dr. Holtorf mentions on his site says it takes an average of 17 years for science to filter down to the practice level.

    Oh, and it's nice to know that you also have occasional moments of self doubt. (_) PR

  • Much self-doubt!

    My thought is that 17 years is from history - with the internet and open access, that is shrinking. True that it is still not enough!

  • Thanks for this. My surgery will only let you have an early test if it is a fasting one. I will print this off and try and use this as a lever.

  • Rod, is this even if you have taken your thyroxine in the morning please? I have begun to take mine at 6-30 when my alarm goes off. So I have as much time as poss before eating and drinking. I had my bloods done at 3-30pm last week the results are abnormally low and they want to take thyroxine off me but I know Im low. Im on 150mg daily. my results were free t4 19.5 0.05 tsh and free t3 4.42 and yes I managed to talk them into the free t3 and 4.

    I have gritty tired eyes that dont focus well, tired, irritable,headaches, muzzy head, not functioning properly again, dropped from 175 a day 2 months ago. any avice would be very gratefully received.

  • In which case, I suggest that on blood test days, you wait until after the blood has been drawn before taking your levothyroxine. And take it straight after the blood has been taken. For one day, do not worry about interaction with food. It makes a difference if they clash every day, but the very odd exception is not so very important.

  • Thank you so much. I will remember as they want another test in 4 months.

  • I have just had thyroid blood tests taken in afternoon;the doc at hospital insisted that it doesnt make a difference when i said that i think it better do tests morn.now i wish i hadnt done it;i didnt realise makes such a huge difference.(now they wont offer a retest for ages ,and i preg.)its so annoying the way they r so sure they know best when they have such little knowledge.

  • If you can, print the above and take it with you next time.

    It would be interesting to hear how he tries to say it is not true then.

    Rod

  • They all seem to live in the Dark Ages for some reason. Arrogant, I believe plays  a part in this.

  • I've had a few, and now always ask for one first thing - I get asked if it's a fasting one - no but happy to fast if I get in early! (besides can't do breakfast anyway). Yes if it's Thyroid they don't think it has to be early. (we know different!)

    I have an ENT appointment every 6 months after my PT op so ask for tests at my surgery beforehand, one time I got a form to take to the hospital, great I thought I'd get to the path lab early but there was a queue! Last time I missed getting in on time so ENT sent me for tests after my appointment at noon - haven't bothered getting those as know they''ll be low. (& they didn't get back to me!) If you look at my profile you can see when I didn't get there early (TSH 3 something).

    So what I'm wittering on about is.... yes, I agree, early DOES matter and the same time each time would be ideal - but unfortunately it just doesn't happen - but I did get a cancellation for wednesday 9.30am - surgery had no record of last test from hosital of course (btw untreated). J :D

  • I know what you mean.

    Round here we can simply take the form to the path lab and get done on a "next free slot" basis. I have found that if I am there at 08:00 when the door is unlocked, I usually get done within twenty or so minutes. At least one of the warfarin or fasting appointments gets missed fairly soon.

    But there are certain times of year that are worse - apparently March (leading up to end of financial year) is a classic super-busy period.

    Rod

  • or maybe we all just feel like c^@p this time of year - us naked apes need sunshine! :)

  • Took note of what you Rod and others said about this last year and was prescribed on the 8 a.m. app., The one two months earlier was taken late afternoon and considered within satisfactory range.

    In the in between years after carbimazole and before hypo diagnosis (blood test)I had blood taken in afternoon because felt too ill in morning to get there early even when the service was on offer.

    Prior to taking levo and after carbimazole always felt a little better late at night.

    This study is good news but 17 years to filter down, do hope not.

    We all need to print this and take to all apps., and leave plenty copies lying around.

    When I get my Endo app., should he request test on day I will ask to have done early locally.

    Thanks for overcoming your doubt Rod. Now we need more doubt in the Medical Prof., about what they were taught in that one day.

    It is great that the results are back in 48 hrs max now. I wonder is this the same over all UK? Couple of years ago it took 7 to 10 days to get results. Great improvement.

  • In spain they do all blood test first thing in the morning and fasting.

  • Strikes me that for many things, that is the only sane approach.

    Sure, some things hardly change through the day, but a standard "always first thing" approach (with exceptions as needed) would eliminate much of the time of day variation which can be very significant.

    Rod

  • IN 2015 I had a TSH of 3.27 (range was 0.5 to 5.5). this test was done in the afternoon.  So this year, I was at the lab by 8:00 and had my blood drawn immediately. I'm hoping that the result will be more accurate with this early morning draw. I'm so fatigued I can't even walk across a room without getting totally breathless and dizzy. I'm no doctor, but just have a gut feeling that it's my thyroid. My doctor is leaving to go to another facility in July, so I'll get a new doctor at that time..I think that's a good thing, because the doctor I have now has no empathy for me. I'm going to choose a male doctor this time, just to see if I can find an advocate and usually those are males for females. (Heroes, if you will.) I'll post my results when I get them back. Thanks for listening...hang in there, all!

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