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We should be able to test our blood for PFAS on a regular basis and our doctors should be able to let us know if we need to filter our blood. But PFAS testing

We should be able to test our blood for PFAS on a regular basis and our doctors should be able to let us know if we need to filter our blood. But PFAS testing is not the norm? Per a Tedx talk on this subject: https://www.nrdc.org/experts/anna-reade/pfas-blood-tests-needed-denied https://www.nrdc.org/experts/anna-reade/pfas-blood-tests-nee... >> Unfortunately, a PFAS blood test is not a routine lab test that can be processed by your local lab and covered by your health insurance. In fact, there are only a handful of labs certified to test for PFAS in blood and the out of pocket cost for this test is out of reach for most people.

snarf21 5y ago
We should all get annual blood tests so we can track variance from out baselines.
- arcticbull 5y ago
  Probably not, honestly. For most tests, the risks associated with a false positive outweigh the benefits of marginally earlier detection. Humans aren't precise machines, each person has different values and different value ranges for standard measurements - and asymptomatic deviations frequently mean nothing whatsoever. On the other hand investigations can be invasive, painful, risky and expensive. There's a reason most tests aren't recommended for folks outside certain risk categories (age, family history, etc). And in a litigious society like America, it's not because it's expensive. There's some specific diseases where there's a lot of data backing this thesis - certain cancers for instance.
  - sodality2 5y ago
    > For most tests, the risks associated with a false positive outweigh the benefits of marginally earlier detection. If these tests aren't run, then I am not sure if it would be "marginally earlier", it might be much later or even never that the problem is discovered.
    - plonk 5y ago
      If they are run, the results could be uninformative (https://en.wikipedia.org/wiki/Base_rate_fallacy https://en.wikipedia.org/wiki/Base_rate_fallacy). Too many false positives could lead to risky treatment and be dangerous. Testing each positive again would still create false positives. I don't know the numbers in this case, but I wouldn't be surprised if accurate mass testing were impractically expensive.
      - closedloop129 5y ago
        This should only be a problem if you don't adjust the models. If you run a huge number of tests, you can create far more detailed models and thus reduce the false positive rate. Ideally, all chemical processes in the body could be known and we could have an almost "mechanical" model of the body. How else but with more testing can be reach that knowledge?
        plonk 5y ago
        > This should only be a problem if you don't adjust the models. If you run a huge number of tests, you can create far more detailed models and thus reduce the false positive rate. Can you? The problem is the test's sensitivity and specificity, there's not much statistical work to do after the test on a single case. It's not an advanced model deciding whether you're sick or not. > Ideally, all chemical processes in the body could be known and we could have an almost "mechanical" model of the body. How else but with more testing can be reach that knowledge? Yeah, ideally we would. Not a doctor, but as far as I can tell, we're a thousand years away from that.
    - wirelesspotat 5y ago
      The video in this comment provides some good examples for why the risks associated with a false positive can be pretty significant: https://news.ycombinator.com/item?id=31126368 https://news.ycombinator.com/item?id=31126368
  - tedunangst 5y ago
    That's the whole point of establishing a baseline.
    - deleted 5y ago
      [deleted]
    - solveit 5y ago
      I don't know why this comment is downvoted. Let me elaborate a little on what I think they meant. All the risks associated with false positives (other than the side effects of actually drawing blood once a year, which I think is negligible) can be removed by simply not overreacting. Find a cancer? Well, consider not subjecting yourself to chemo just to get rid of it. Some cancers will kill you by winter, some will just stay there until you die of something else. How will we know which is which? By testing lots of people over long periods of time to see what's harmless and what's actually really bad. Or as the previous commenter said: "That's the whole point of establishing a baseline."
      - arcticbull 5y ago
        The parents premise is wrong. You can't just "establish a better baseline" and "if the test says you might have cancer don't worry about it maybe?" The former is hampered by base rate fallacy [1] (specifically the part about disease in a low-incidence population) and the in the latter, if you're going to disregard the outcome why are you testing? A concrete example is the NHS recommends against the PSA prostate cancer antigen screening test completely for everyone of any age because this test does more harm than good. They have a good write-up on why. [2] Generally I agree this data should be collected, but aggregated and not used for individual treatments. [1] https://en.wikipedia.org/wiki/Base_rate_fallacy https://en.wikipedia.org/wiki/Base_rate_fallacy [2] https://www.nhs.uk/conditions/prostate-cancer/psa-testing/ https://www.nhs.uk/conditions/prostate-cancer/psa-testing/
        tedunangst 5y ago
        I guess I should have been more clear that by establishing a baseline I did not mean take one test and then have surgery.
  - spockz 5y ago
    I think the value in regular blood tests is to get an idea of what normal values are for you specifically. For some diseases/conditions the blood levels have such a big range that it is more useful to know the delta. We hardly ever measure the “good” or stable cases so when we start testing stuff when we are ill there is very little data on what is normal or even normal for you. Ive heard of cars where due to family history someone preemptively screened on certain blood values. When those changed they knew something was up, even though the value was still within normal range it was up 100x for them.
    - arcticbull 5y ago
      Here's a good explanation of why it's not a good idea from Medlife Crisis. [1] h/t wirelesspotat. [1] https://www.youtube.com/watch?v=rW3DGnHO2iY https://www.youtube.com/watch?v=rW3DGnHO2iY
  - adrianN 5y ago
    How well do we actually know "normal" values if we don't have the broad data that regular blood tests for everyone could give us?
- wirelesspotat 5y ago
  There's a great video from Medlife Crisis about why this might not be a good idea "The Problem With Silicon Valley Medicine": https://www.youtube.com/watch?v=rW3DGnHO2iY https://www.youtube.com/watch?v=rW3DGnHO2iY
- pkaye 5y ago
  Even is the US, a metabolic panel of about 15-20 basic blood tests is only about $40. You an order it online and go to a local lab to get blood drawn.
roywiggins 5y ago
Nobody knows the threshold above which intervening is a good idea or worth the effort, so universal testing seems like jumping the gun a little.
- sdenton4 5y ago
  People said similar things about lead...
  - mrmuagi 5y ago
    The people vested in using lead in fuel said so out of profit motive, but it seems lead was widely known to be harmful for hundreads of years [0] before it was using it fuel. [0] https://www.youtube.com/watch?v=IV3dnLzthDA https://www.youtube.com/watch?v=IV3dnLzthDA
  - roywiggins 5y ago
    We don't preemptively test everyone for lead either!
    - dibujante 5y ago
      This is true, although I would prefer to still test everyone for plausibly important things to feed data analysts who might eventually discover something useful.
      - roywiggins 5y ago
        That's a lot of blood draws to ask of people, for something that doesn't even have a hypothesis. There are studies like the UK biobank that are trying to collect longitudinal information about a huge number of people, but they're volunteers.
      - sorenn111 5y ago
        I'd love for that to be true, but there's a good chance that in doing broad tests you are incurring costs (both to patient health and cost [whether paid by patient, gov, or insurance company]) without getting anything beyond noisy data without useful signal
Exuma 5y ago
What do they cost?
- droopyEyelids 5y ago
  If you were curious, a quick search gave me results in the range of $300-$400 https://empowerdxlab.com/products/product/pfas-exposure-test https://empowerdxlab.com/products/product/pfas-exposure-test
- ComputerGuru 5y ago
  I just called Quest Diagnostics and they charge $679 w/out insurance for the PFAS panel [0]. [0]: https://testdirectory.questdiagnostics.com/test/test-detail/39307/perfluoroalkyl-substances-pfas-serumplasma?q=PFAS&cc=MASTER https://testdirectory.questdiagnostics.com/test/test-detail/...

snarf21 5y ago

We should all get annual blood tests so we can track variance from out baselines.

arcticbull 5y ago
Probably not, honestly. For most tests, the risks associated with a false positive outweigh the benefits of marginally earlier detection. Humans aren't precise machines, each person has different values and different value ranges for standard measurements - and asymptomatic deviations frequently mean nothing whatsoever. On the other hand investigations can be invasive, painful, risky and expensive. There's a reason most tests aren't recommended for folks outside certain risk categories (age, family history, etc). And in a litigious society like America, it's not because it's expensive. There's some specific diseases where there's a lot of data backing this thesis - certain cancers for instance.
- sodality2 5y ago
  > For most tests, the risks associated with a false positive outweigh the benefits of marginally earlier detection. If these tests aren't run, then I am not sure if it would be "marginally earlier", it might be much later or even never that the problem is discovered.
  - plonk 5y ago
    If they are run, the results could be uninformative (https://en.wikipedia.org/wiki/Base_rate_fallacy https://en.wikipedia.org/wiki/Base_rate_fallacy). Too many false positives could lead to risky treatment and be dangerous. Testing each positive again would still create false positives. I don't know the numbers in this case, but I wouldn't be surprised if accurate mass testing were impractically expensive.
    - closedloop129 5y ago
      This should only be a problem if you don't adjust the models. If you run a huge number of tests, you can create far more detailed models and thus reduce the false positive rate. Ideally, all chemical processes in the body could be known and we could have an almost "mechanical" model of the body. How else but with more testing can be reach that knowledge?
      - plonk 5y ago
        > This should only be a problem if you don't adjust the models. If you run a huge number of tests, you can create far more detailed models and thus reduce the false positive rate. Can you? The problem is the test's sensitivity and specificity, there's not much statistical work to do after the test on a single case. It's not an advanced model deciding whether you're sick or not. > Ideally, all chemical processes in the body could be known and we could have an almost "mechanical" model of the body. How else but with more testing can be reach that knowledge? Yeah, ideally we would. Not a doctor, but as far as I can tell, we're a thousand years away from that.
  - wirelesspotat 5y ago
    The video in this comment provides some good examples for why the risks associated with a false positive can be pretty significant: https://news.ycombinator.com/item?id=31126368 https://news.ycombinator.com/item?id=31126368
- tedunangst 5y ago
  That's the whole point of establishing a baseline.
  - deleted 5y ago
    [deleted]
  - solveit 5y ago
    I don't know why this comment is downvoted. Let me elaborate a little on what I think they meant. All the risks associated with false positives (other than the side effects of actually drawing blood once a year, which I think is negligible) can be removed by simply not overreacting. Find a cancer? Well, consider not subjecting yourself to chemo just to get rid of it. Some cancers will kill you by winter, some will just stay there until you die of something else. How will we know which is which? By testing lots of people over long periods of time to see what's harmless and what's actually really bad. Or as the previous commenter said: "That's the whole point of establishing a baseline."
    - arcticbull 5y ago
      The parents premise is wrong. You can't just "establish a better baseline" and "if the test says you might have cancer don't worry about it maybe?" The former is hampered by base rate fallacy [1] (specifically the part about disease in a low-incidence population) and the in the latter, if you're going to disregard the outcome why are you testing? A concrete example is the NHS recommends against the PSA prostate cancer antigen screening test completely for everyone of any age because this test does more harm than good. They have a good write-up on why. [2] Generally I agree this data should be collected, but aggregated and not used for individual treatments. [1] https://en.wikipedia.org/wiki/Base_rate_fallacy https://en.wikipedia.org/wiki/Base_rate_fallacy [2] https://www.nhs.uk/conditions/prostate-cancer/psa-testing/ https://www.nhs.uk/conditions/prostate-cancer/psa-testing/
      - tedunangst 5y ago
        I guess I should have been more clear that by establishing a baseline I did not mean take one test and then have surgery.
- spockz 5y ago
  I think the value in regular blood tests is to get an idea of what normal values are for you specifically. For some diseases/conditions the blood levels have such a big range that it is more useful to know the delta. We hardly ever measure the “good” or stable cases so when we start testing stuff when we are ill there is very little data on what is normal or even normal for you. Ive heard of cars where due to family history someone preemptively screened on certain blood values. When those changed they knew something was up, even though the value was still within normal range it was up 100x for them.
  - arcticbull 5y ago
    Here's a good explanation of why it's not a good idea from Medlife Crisis. [1] h/t wirelesspotat. [1] https://www.youtube.com/watch?v=rW3DGnHO2iY https://www.youtube.com/watch?v=rW3DGnHO2iY
- adrianN 5y ago
  How well do we actually know "normal" values if we don't have the broad data that regular blood tests for everyone could give us?
wirelesspotat 5y ago
There's a great video from Medlife Crisis about why this might not be a good idea "The Problem With Silicon Valley Medicine": https://www.youtube.com/watch?v=rW3DGnHO2iY https://www.youtube.com/watch?v=rW3DGnHO2iY
pkaye 5y ago
Even is the US, a metabolic panel of about 15-20 basic blood tests is only about $40. You an order it online and go to a local lab to get blood drawn.

roywiggins 5y ago

Nobody knows the threshold above which intervening is a good idea or worth the effort, so universal testing seems like jumping the gun a little.

sdenton4 5y ago
People said similar things about lead...
- mrmuagi 5y ago
  The people vested in using lead in fuel said so out of profit motive, but it seems lead was widely known to be harmful for hundreads of years [0] before it was using it fuel. [0] https://www.youtube.com/watch?v=IV3dnLzthDA https://www.youtube.com/watch?v=IV3dnLzthDA
- roywiggins 5y ago
  We don't preemptively test everyone for lead either!
  - dibujante 5y ago
    This is true, although I would prefer to still test everyone for plausibly important things to feed data analysts who might eventually discover something useful.
    - roywiggins 5y ago
      That's a lot of blood draws to ask of people, for something that doesn't even have a hypothesis. There are studies like the UK biobank that are trying to collect longitudinal information about a huge number of people, but they're volunteers.
    - sorenn111 5y ago
      I'd love for that to be true, but there's a good chance that in doing broad tests you are incurring costs (both to patient health and cost [whether paid by patient, gov, or insurance company]) without getting anything beyond noisy data without useful signal

Exuma 5y ago

What do they cost?

droopyEyelids 5y ago
If you were curious, a quick search gave me results in the range of $300-$400 https://empowerdxlab.com/products/product/pfas-exposure-test https://empowerdxlab.com/products/product/pfas-exposure-test
ComputerGuru 5y ago
I just called Quest Diagnostics and they charge $679 w/out insurance for the PFAS panel [0]. [0]: https://testdirectory.questdiagnostics.com/test/test-detail/39307/perfluoroalkyl-substances-pfas-serumplasma?q=PFAS&cc=MASTER https://testdirectory.questdiagnostics.com/test/test-detail/...