Why does my private thyroid test differ from nhs one?

Cutting long story short, i recently had some private thyroid tests done which showed.my tsh as 0.9 range to 4.2 ... Then had my routine one done via doc couple weeks later which showed tsh of 1.84 range to 5.5 .... I thought the different tsh is cos of different ranges , but why would it make such a difference ?

12 Replies

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  • The time of day you have your test can also make quite a difference. The earlier in the day the higher the TSH.

    Moggie x

  • Yes the nhs one was done in morning, the other in the afternoon,, that's one big difference ,, just shows how you can't just rely on a tsh ,,

  • Thank you for this,, further proof that this test is flawed,,,

  • Well that seems to explain it then, with different times and different ranges you have your answer.

    Moggie x

  • Most important, Ian, don't do the NHS in the afternoon - ever - or the GP will reduce your thyroxine! It's very useful that it actually happened because you have definitive proof that it really DOES matter when you do the bloods.

  • Agreed,, thanks for your reply !

  • That reply has proven so useful to me, as I had my last b/test done at 2,30 pm and lo and behold my doc insisited on lowering my thyroxine 25 grams.... not felt good since.

  • hi ian , proof positive that timing of blood tests can influence all of the results that the current system use as treatment guidelines must be part of the diagnosis....something that many people on this site have been banging on about for a long time....alan

  • What amazes me is that when the tsh is to high,, no one is in a rush to increase dose but once too low apparently,, they rush to lower dose so much . If it's too high they say oh come back in few months and re test but if low,, it's reduced there and then... There are health risks with low thyroid too !

  • If I remember rightly, maybe someone can agree/disagree with this, the difference between early morning and late morning TSH results can be around 2.0, so your private TSH could have been around 2.9 had you have had the test at 8am.

    Have just remembered this paper:

    Research by Scobbo et. al. in 2004 showed that TSH tests declined in 97 of 100 of the people studied -- by an average of 26.39% -- when compared to early morning, fasting, TSH test results. This resulted in as many as 6% of patients being reclassified from the diagnosis of subclinical hypothyroidism to "normal."

  • And now the tsh has come back at that level,, I'm thinking maybe i need an increase in Levo,, am on 75 but def been feeling bit sluggish lately,,

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