I have been diagnosed hypothyroid for about 20yrs My bloods are checked frequent especially as I have RA and presently anaemic.
I have never been told not to take thyroxine before blood test so I have always taken it. I've read many times now the advice about NOT before blood test. Is this right? I think I will ring my practice prior to my next test which is soon Have I been wrong all these yrs??
The thing is, if you take your levo within 24 hours before the test, all you will be testing is the last dose you took, not what is normally in your system. Doctors swear it doesn't make any different but it does to the FT4 - if your doctor tests the FT4. If all he tested is the TSH, then no, it doesn't matter.
To get the highest TSH, you need to have your blood draw as early in the morning as possible, and fast over-night. TSH is highest early on, and drops throughout the day. It also drops after eating. But, doctors don't know that, either.
greygoose , that is so interesting and so informative . I did not know that eating drops TSH . Most Dr's will tell you it does not make a difference . That's how much Dr's know . Why am I not surprised ? THANK YOU FOR SHARING !!!!
Don't take the blame on yourself!
It is quite obvious if you look at research and things like how FT4 peaks around two hours after taking the tablet. But why should any patient have to find this out for themselves? Worse, to be told it doesn't matter by someone who really should know better.
By all means ask your practice, but don't expect the same answer as so many here would give you.
Thank you for that Its interesting and mine has been erratic in the pas.
If we had a blood test ten times in one day, the TSH would be different as it reduces. helvella has responded succinctly as usual - research is never read and doctors have been told that only the TSH and T4 are sufficient. They never treat clinical symptoms as they know none: so many people are left high and dry if their dose of levothyroxine is inadequate to alleviate symptoms but, of course, they are given other medications for the remaining symptoms.
All of us on this forum now know differently and how to get the best out of a blood test.
Now the question I have is what happens with TSH when working night shift? My feeling is that it would reduce as you are obviously more active that you would be when sleeping.
I usually make a point of getting bloods done after at least 48 hours off duty to get back into "normal" mode.
Last time I remember looking, I didn't find anything very specific on this issue. That has now changed!
Conclusions
In conclusion, we found that night shift work was associated with increased TSH levels among female workers at an university hospital. We believe that these findings may help increase awareness of thyroid disease occurrence among night shift workers. Furthermore, we hope that this study can provide the foundation for detailed studies regarding the effects of night shift work on thyroid function and disease, and the association between night shift work duration and TSH levels.
ncbi.nlm.nih.gov/pmc/articl...
Thanks for that link helvella . Will read it after I had a good sleep. That might explain why 2 of my co-workers also has thyroid issues. That makes it 30% of the night staff. That I know of.
Although this doesn't refer to working night shift, this paper does discuss the changes in the various thyroid-related hormones that are produced over a 24-hour period in healthy people :
academic.oup.com/jcem/artic...
There is a PDF available if you want to download it or print it out for any reason.
I posed this very question last year when I was a newbie as on a couple of occasions I had been for blood tests straight from a night shift and another couple were early afternoon after a day shift, bless my naivety! I was still getting optimised so think my results were all over the shop anyway. I work a 10 day rolling pattern of 2 days 2 lates and 2 nights, a flaming nightmare at first. I take my levo around midday as its the one l time I can guarantee to a) be awake and b) ensure the recomended wait times to avoid absorption issues from eating and drinking conflicts. It seems to work even though my bloods are usually taken only about 19 hours after last dose.
Unfortunately, I didnt get any definitive answers other than TSH changes relatively slowly, it might be different if you are on permanent nights as your circadian rhythm has more chance to reset especislly if you sleep well during the day. I decided the best plan was to be tested at the same time on my second rest day so 24ish hours after finishing nights. Consistency was the main recommendation so results are comparable.
I dont have Hashi, I am in the odd 'no idea why' 10%. I have been doing rolling shifts for 16 years though 🤔🤔 Click to my profile and the question is in one of my earlier posts if you want to see the replies I got.
I an still trying to get diagnosed. You can see my results on my post. I am working 7 shifts over a fortnight for 10 years now.
Getting the feeling nightshifts messes about more with the circadian rhythm that it seems.
Will check your post.
Thanks.
I stopped taking medication before a test on the advice of a Endo many years ago. She was the one that told me that it can give a false reading. My GP/Nurse would argue otherwise. But I do find that by not taking it before the test, it does give a more accurate result. I just take it at the first opportunity after the test.
I just don't understand why in most cases they only test TSH levels. My level is naturally suppressed as I only have a partial non working thyroid. .
There seem to be two reasons for testing only TSH:
1) Cost - a single TSH test is less cost than TSH plus FT4 plus FT3;
2) Lack of any understanding of what they would do with three numbers! After all, many guideline documents talk almost exclusively about TSH level and getting that in range. So if FT4 and FT3 are high/low/one high & one low but TSH is in range, what is there to be done?
MintyC, I found your post very interesting. Like you I was never told to fast before my 1st Thyroid blood test in 2003, or subsequently. Back then blood tests were only once annually, never early morning either, So had also taken my Levo on same day. I only learnt while living abroad, around 2014 from here on TUK,about the do's and don't's, also which additional things to get tested. Much of my own known prior health conditions research involved American websitelinks via Wikipedia, not Google. I also have at least 3 proven Autoimmune conditions, TB, HASHIMOTOS & Thrombocytopenia.
Now living back in UK since last October, only a mile from previous U.K. Address, complete with last 8yrs of extensive quarterly taken blood tests, at Easter my new registered GP at a different practice has sent me to see several Consultants, which included an Endocrinologist - but still both are only interested in TSH results!
Also like you, I've been told recently i have RA and the Haematologist thinks I'm anaemic without having a specific Ferritin test, but wrote to my GP because he was wants me put on iron tablets. At present, my "gut instinct" is stopping me taking them (I'd been phoned by surgery to say a prescription had been sent direct to the local chemist for me to collect them, which I did).
A 17 July haemoglobin (HB A1c level blood test - for which the standardisation has been changed was, it seems a Diabetes test, which came back higher in range though negative, for Type 1/2, also says if result is lower, it does not exc Diabetes, it would need a backup glucose test - as well as a plasma glucose test on 3/7 , loads of fingerprick tests daily while in hospital May/June after a massive gastrointestinal haemorrhage and ALL but 1 of above say I am not diabetic - nothing specific amongst other separate results there for Thyroid though!
As we all say, our GP's, Consultants also, want to ignore Anything other than TSH levels, thereby unwilling to test and prescribe properly.
They and N.I.C.E guidelines are all doing so at their own peril and risk to further patient ill health. 'Clinical Excellence' - Clinical yes - Excellent NO.
The numbers of women of all ages now presenting with, apparently, Thyroid conditions, are steadily on the increase - as are the numbers of patients presenting with many other mostly preventable or properly treatable conditions, through ignorance or mismanagement .
It's well past Time for the Medical Profession to listen to Patients with chronic auto-immune conditions. We know how our bodies feel and react to external as well as internal substances ingested by mouth or skin. They don't!
So keep on telling them - be true to yourself - remember that persistence overcomes resistance.
That is just astonishing I have found you Sambs I can echo every word you say. I have been through hell lately and so have you Yes they sympathize but the general feeling that the Drs don't understand the severity of the last few years Recently they bombarded me with phone calls about my Hb 8 and WC being high Then organized an endoscopy 2 colonoscopy CT xray. The dr said my bowel was twisted up baldly enlarged with extensive leaky gut. I not surprised anymore because I go to bed with heat pad my stomach hurts so much. Sometimes I'm jaundice and I know the chronic burning up is autoimmune but its stomach also. My daughter was diagnosed diabetic about 3 yrs ago she would test my blood with her prick test and it was always not in range. Do you suffer with heat intolerance where its like a switch and you feel your chest pounds and throat pounding a blanket of heat pours down your veins swell face reddens and you have to sit back for at least 20mins sometimes my skin looks like Ive been in the sun Hyperlipoedama of sorts?? What treatment are you taking for your RA?? I'm starting methotrexate in Sept. How are you now in general do you suffer with inflammation? So many questions!!
I've read most of your posts SAMBS you are so brave You've dealt with so much and in France. I understand your reluctance to take the many drugs flown for it just seems to make things worse I think I have haemolytic anaemia but not sure. The last couple of yrs my feet are badly deformed My knees are like balloons
I admire your skills at researching your own issues. I know my own body changes I read but despite being a nurse 20yrs ago the science goes over my head its too challenging for me I will watch your posts and wish you loads of good luck and love. Xxxx
Well my bloods day came have to admit I was bit dazed usual brain fog so took my 250. But I got the older (she's same birth yr as me so its our joke) She said You must take your full dose the blood will tell us your level and if your thyroid is up or down. Make sense to me but I do fully get others scientific points coz you lot know more than my GP. May I ask someone In jan my hb dropped to 8 little panic even Rheumy rang me.
All l cud say was I thought I had flu my temp went up couldn't walk dizzy It was like old fashioned flu. Week later picked up
It happened again my temp soared I looked awful All I drank was h20. Could this be haemoloytic anaemia my feet where blue but my body was really hot to touch.
Starting mxt 7th Sept if my hb is low (its about 9 last count) will I still start it?? My head is puddled even GP said see Rheumy Im not sure.
Another blood test but already taking thyroxine? 
Why do I have to lower Thyroxine (update)..Blood tests results.
Having a blood test. When do I take my Levo?
Taking thyroxine after having blood test not before
