Fingerprick tests accurate?

[mountainice]

I have just read this:

Capillary Fingerprick Tests

'A somewhat controversial test available some places uses fingerprick rather than venous blood draw samples to evaluate thyroid function.9 Proponents of this testing, also called a blood spot test, believe that this testing prevents the breakdown of TSH during the time between when blood is drawn and when it is that could lead to erroneous results. Since the test is not currently widely available, it's unknown exactly how well the test compares with conventional TSH testing.'

Does it mean I can't rely on my Medichecks test?

[msmono]

This is interesting. I don't have an answer I'm afraid as I've just switched to Medichecks because they're cheaper than LetsGetChecked who use The Doctors Laboratory (which many G.P.s/NHS use). I wonder what is mean by 'preventing the breakdown of TSH' i.e does it mean it will give a higher or lower TSH reading. Might be worth searching on here for other Medichecks accuracy experiences.

[mountainice in reply to msmono]

Not heard of LetsGetChecked, I will make a note just in case.

[Jazzw]

No, it doesn’t mean that. With Medichecks and Blue Horizon microtainer tests you fill a small tube with around 15-20 drops of blood. That’s not a “spot” test.

I had reason to look this up the other day—I’ll try to find the post which explains why Medichecks and Blue Horizon tests are just as reliable as blood tests done using venous blood. Back shortly...

[Jazzw]

Here you go. healthunlocked.com/thyroidu...

For the most comprehensive answer, scroll to the last reply in the thread.

[mountainice in reply to Jazzw]

Thank you

[SeasideSusie Remembering]

If it's any help, I (and other members) have done a GP venous blood test and a private fingerprick test either the same day or within a few days and had virtually the same results with both tests. I have no concerns with the accuracy of fingerprick tests.

Here's an example of my tests done 5 days apart, different ranges so I've added in the % through range, and my TSH is always suppressed so the levels are the lowest their testing equipment goes:

GP TEST done at 9.15am fasting, no Levo for 24 hours, no T3 for 12 hours.

TSH: <0.02 (0.35-5.5)

FT4: 14.2 (7-17) = 72%

FT3: 5.8 (3.5-6.5) = 76%

MEDICHECKS done at 8.40am fasting, no Levo for 24 hours, no T3 for 12 hours.

TSH: <0.005 (0.27-4.2)

FT4: 19.5 (12-22) = 75%

FT3: 6.1 (3.1-6.8) = 81%

believe that this testing prevents the breakdown of TSH during the time between when blood is drawn and when it is * that could lead to erroneous results.

Is there a bit missed out where I've marked it *

As TSH is really only useful for diagnosis, and it's FT4 and FT3 that are the important results when on thyroid hormone replacement, if they're referring to just the TSH result that could be erroneous then that's not necessarily a concern for many members anyway.

[mountainice in reply to SeasideSusie]

It was missed out too in the text where I read it.

[mountainice]

Thanks everyone.

[MaisieGray]

As has been said, the quote refers to blood spot testing, which isn't used for thyroid functions & etc tests. However, a commonly used vit D test offered to the public by City Assays is a finger spot test. City Assays is an NHS laboratory based in NHS City Hospital in Birmingham, and is part of Black Country Pathology Services serving four NHS Trusts. Its Vitamin D test service to the public has been operating since 2011 and carries a CE mark, and as it states on its webiste, "Results are closely aligned to serum results. Ranges for serum and blood spot are comparable". So I think for the purpose of members here, we needn't be concerned about the results we're getting from the labs generally suggested here.

[mountainice in reply to MaisieGray]

ok