Non fasting blood tests due. What if I decide to fast? Would it be to me advantage??

Please see my posting "GP would not refer..." (sorry very lengthy - I was upset!) as I have insisted on further tests as I am supposed to feel normal now - but not.

I have been asked to NOT fast, but what difference will it make if I do, will it help my case or not? Can they tell if I have fasted? :O

She insisted that all my results were normal, and to 'pacify' me agreed to VitD, Cacium, B12 (I think) Ferrous and a couple of other tests. She was vague.

Thank you,


8 Replies

  • I really do not have any idea. The only time I am asked to do a fast before a blood test is if they are going to check my cholesterol, so all my other tests have been done without fasting.

    I am sorry you were upset and hope you settle down a little over the weekend.


  • Which bloods are you having done?

  • Just added to question above. Thanks.

  • I fasted, not intentionally of course, I dnt eat breakfast, I do feel it will make a difference to your results, my came back out of sinc. Dont think they can tell, after all I presume its the TSH test you are having done?


  • Hi,no the labs won't test TSH again because I'm 'normal' at 3.7. Also see my response to all below ... somewhere. ? )


    x x

  • Hi Fasting used to be for cholesterol and diabetess tests. Now, the new rules are that fasting is not needed. I used to fast before my diabetes so severe, now told I must not, there is no difference in my results. However I know not to take any thyroid meds or Beta blockers on the morning of the test until afterwards. I have so many blood tests ,the results are blatant.I also have a lot of other weekly tests and the other meds I have ( a great many ) do not effect those tests.


  • In my experience a fasting blood test measures you fat and sugar levels in your blood, it is for your cholesterol levels, I don't think, as you are measuring your thyroxin levels it will make any difference to your blood results for this test but not eating sensibly WILL make a difference to your well being. 'They' will only know if you tell them and why would you want to fast anyway? Thyroid problems already play havoc with your metabolism.

  • Thank you every one for the responses, and explaining to me before the tests.

    Because of waves of nausea (??) since developing HypoT. I have only a drink in the morning until my body wakes up. Usually about break time - 10 ish. Otherwise I have a healthy appetite! Some blips have been pointed out by other good people on this site and I have made a note - but I just wondered if it would make a difference.

    Only if fasting showed clearly hidden blips in previous thyroid tests would I have fasted.

    The tests are not for Cholesterol or Diabetes, I know they are OK. So that's prob. why I have been told not to bother with fasting; as it's not necessary.

    That's absolutely fine.

    Thank you all.


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