More gloomy news I'm afraid

As I rather ranted on about at the Thyroid UK conference in 2014, the inability of the various (virtually all tenth rate or less) manufacturers to produce consistent free T4 and free T3 tests, combined with the complacent ignorance of the medical users as to the quality of what tests they actually employ, has led to confusion and poorer diagnostic performance than is acceptable. Thus more consistent TSH has dominated diagnosis. Prof L Thienpont has over the last years been busy collaborating with these manufacturers to try to get some better consistency between products. Free T4 was first in line (products vary by up to 25%). Free T3 was nowhere (manufacturers excuse - few people use the test, hardly any [importantly] in the States, so no pressure to improve from an entirely unacceptable 60% variation source-to-source even though this is quite technically possible). However even though the manufacturers have been dragged into line in theory, they are still dragging their heels over actually doing anything concrete and rationalisation of even Free T4 seems years away. FreeT3 - forget it! In diagnosis, it's like going to the greengrocers in town to get 1 kilo of potatoes, and getting anything between 0.8 and 1.2 kilos. So I hope you can see what an uphill struggle it will be to get the dozy collection of incompetent manufacturers, fast-asleep regulators and complacently ignorant end-users to actually make thyroid function testing acceptably accurate and consistent. As an ex-physical biochemist and molecular biologist, I can tell you my then colleagues would be rolling in the aisles in side-splitting mirth at the deficiencies and the resulting nonsensical situation of using bad test quality and compromising diagnostic efficiency even more than need happen.

19 Replies

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  • :-(

  • I do remember you mentioning at the Conference that the T3 test could be 50% out either way - and that results were only as good as the people reviewing them !

    This clarification is good. So back to clinical symptoms tomorrow then ? :-)

  • ha! me too - was just about to get some blood tests done, don't think I'll bother now

  • I agree whole heartedly GP s doctors and endos should go back to the old way of diagnosis by basal temperature pulse and signs and symptoms . All my many blood tests were normal for years and it wasn't till I found a doctor who would go against the blood tests and diagnose by my symptoms that I became well ! I believe there are still some doctors out there that will give patients a trial of T4 T3 or NDT and I say good on them! I realize of course giving someone meds that blood tests say they do not need has to come into the equation but it has been proved( by my research) that starting on a low dose and upping it gradually will not do any harm . I read a statement written by dr Robert utiger , the clinician and researcher who developed the TSH and T4 blood tests , he said " I hope doctors are not going by these blood tests alone the best test is a trial of thyroid replacement hormone ( either T4 T3 or NDT) " Jay

  • Scary to say the least.

  • I'm guessing you must use different assays/equipment for research than these commercially available ones? i.e. where the repeatability/accuracy of (published) research test results are very good/consistent and of high quality. I would have expected a lot less variance than that. It asks the question of why do the test in the first place. FT3 variation of 60% seems almost unbelievable. I've read people saying that their endo has stated there's little to no point in testing FT3 due to the test being unreliable, and that TSH was a more accurate way of establishing thyroid function. I thought this was purely to save money but maybe not and it's down to poor test quality.

    Not sure but feel we're all doomed! Or we can do as both Marz and bobsmydog suggest and go by clinical symptoms and stop wasting money on "pointless?" blood tests.

    I hope the manufacturers buck their ideas up!

  • We used a commercial test that was closest to being adequate for the job. Not all manufacturers are terrible, just nearly all. The problem is the few good get swamped by the many terrible.

  • What are your team's criteria for choosing a particular commercial test that's adequate for your work? I do wonder how many labs have your experience in choosing testing methods! It does seem a strange situation where terrible tests exist in this world. Anyway, I may have misread your original post, so, just to clarify - are the test results for FT4 & FT3 repeatable between tests from the same manufacturer using the same blood sample? And therefore the inaccuracy is only present between identical tests from different manufacturers.

    I suppose standardising a test is difficult? In terms of international standards of calibration, etc. I don't know...as I understand the FTx tests involve statistical methods based on a population, which presumably, as you suggest, differ from manufacturer to manufacturer.

    Would the absolute value measured (of say FT4) be similar between manufacturers? i.e. is it a direct measurement of absolute FT4/3?

    Or, are the measurements made based relative to a statistical percentile in a population? i.e. FT3 test results are relative to population A. Or does it provide both absolute and relative measurements ?

    Sorry for all the questions - I'm just interested.

  • That is right. Individual tests from individual manufacturers are consistent batch to batch, occasion to occasion. Its the intrinsic differences BETWEEN manufacturers' products that cause problems if you are tested by more than one method esp FT3. The basic problem for FT4 and FT3 tests is that there isn't an international standard. There is for TSH thus its performance between manufacturers is better. So what is a better FT4 and FT3 test? Absolute calibration is one thing and differs between different products: but there are other potential problems which are hugely technical. Briefly, do all such tests act independently of the T4 and T3 bound to the transport proteins? They must do to be valid. Too often they do not and therefore are potentially distorted when the transport proteins and their hormone loads are different from the average. As far as our studies are concerned, we are dealing with overwhelmingly average patients in this regard, so any distortions are minimal and outliers don't affect the overall answers. To get a reference range by any method you simply choose say 100+ normals - assuming that virtually all will be average or close to it - by great good fortune that is true but on occasion you can get a maverick and if your assay isn't good it will show up.

  • Thanks diogenes for this. You're getting technical but not overly technical!, which is good to a layperson. I now see where some of the technical problems can come from and also how the patients in your studies sit nicely in the population with minimal outliers/extremes in the data. Any outliers are presumably so minimal that it doesn't skew the results to any degree worthy of note. I suppose if tests are not acting independently of the bound hormones then the overall result will have intrinsic errors whereby the unbound hormone measurement has an element of bound hormone in the result. This could presumably lead to an over-measurement of, say, FT3.

  • If I use the same test lab each time, will I be getting any useful information? Or am I still wasting my time/money?

  • In a word yes the info will be OK (unless you are a very rare person) provided only one test type is used. It's when you get measured by different methods e.g. from different labs that real problems occur. For many of the "bad" tests, performance is worse the further you are away from an "average" person re your blood content of hormone transporting proteins.

  • Thanks, I just prefer to still have the numbers as well as look at my symptoms

  • Diogenes, are the tests used by hospital labs likely to be more accurate than commercial labs?

  • This is difficult to comment on, because I don't know how each test was designed. My gut feeling is that I see no reason for speaking generally any one will be better than any other. There will be some tests available that I know are better, because I know the scientists who developed and thoroughly tested them clinically in the most obscure areas .But that level of care and testing before commercial sale is rare indeed. I repeat that for the average sort of person (say 95%) all tests are "OK" in that you will get consistent results. BUT depending on how they were made, they will offer results different from one to another and "extreme" patients may not be well served. Most of you are not "extreme" but by statistics 5% will be.

  • Thank you, Diogenes. 5% of hypothyroid &/or hyperthyroid patients must be a considerable number of ill served patients. It's tragic the manufacturers and labs don't improve the testing which might improve treatment and ease suffering.

  • Only people actually doing the work of you and your colleagues know what disadvantage to patients occurs due to the inefficiency of many who are supposed to be professionals with the continuing illness of patients, giving Big Pharma more profits..

    You are all worth your weight in gold

  • There are vested interests at stake here, did you not know that the manufacturers of levo pay for conferences etc?

  • Not vested interests here; just sheer bumbling incompetence.

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