NHS vs Medichecks Lab Results - big difference

[csj113]

Hi, just wondering if anyone has experience of this they can share. I had fairly major surgery in early November and waited till New Year to let everything stabilise before getting an Advanced Tiredness and Fatigue blood test done at Medichecks. My main reason was to check Ferritin and Folate which have been low (have had iron infusion last May + been taking methylfolate to address this). I realised afterwards this test doesn't include T3 which was annoying so will have to get that done, though mine usually sits about halfway through range (not a chance in hell of getting prescribed T3 in my neck of the woods so I have to run my Levo dose high to feel well). My Ferritin has dropped quite low again (56) post infusion which is disappointing but that's another story. I'm still bleeding heavily each month which doesn't help, but anyhoo, the reason I'm posting is this:

Medichecks:

12/01/2023 T4: 28.9 (12-22)

Medichecks agreed to repeat the test for free and this was the result:

23/02/2023 T4: 24.8 (12-22)

NHS lab (via GP) Greater Glasgow & Clyde area

15/01/2023 T4: 17.7 (9-21)

All tests done 9am, fasted, venous blood draw.

My GP has dismissed the Medichecks results as incorrect and is happy to keep me on current dose (I strongly agree!). He did T3 but it was Total T3 which is all our labs will do - think it was midway through range.

Can anyone comment on this significant discrepancy?

[helvella Administrator Thyroid UK]

I suggest a read of this paper:

Interferences With Thyroid Function Immunoassays: Clinical Implications and Detection Algorithm

Open Access

academic.oup.com/edrv/artic...

By the time you get to the end, you might be amazed when any two tests agree with each other.

More seriously, it provides intellectual and scientific grounds for accepting one result but rejecting another, conflicting, result. However, it still does not provide a definitive answer as to how to decide between two results. (If you could have a dozen tests done using different techniques, that might become obvious. But with only two techniques it is more subtle.)

I suggest you make sure you know exactly which system each test was run on. That might give you a basis for choosing which labs to use in future.

[bantam12]

My Medichecks result have frequently been very different to same tests done at GP and hopsital. I’ve tested it by doing them at the same time and particularly liver enzymes are vastly different, my last GGT test was 220 from Medichecks and 92 from my GP. I’ve just done another thyroid test so will see what that comes up with !

[Knowsnothing]

I think sometimes things can just go skew whiff, I once had some tests done at the hospital and when the results came the consultant said that's absolutely impossible so they had to repeat the bloods and then they were ok.I had some bloods done with monitor my health a few weeks ago then had a test in the NHS and the results from monitor my health were the same, however monitor my health is an NHS lab anyway.

[csj113 in reply to Knowsnothing]

Thanks, bloods can definitely go wrong and it’s inadvisable to trust a single test if it seems out of kilter.

I had a repeat test from Medichecks (their expense) and it’s come back T4 of 24.8 this time so I’m still none the wiser as to my true T4 level. V frustrating.