I can tell you there are at least a couple people on this forum I am confident were railroaded by bad PETH tests from LabCorp. Interestingly the two I am personally aware of both were tested at the same testing facility (in Dallas) but passed the exact same LabCorp tests at other testing facilities the same/next day. What I cannot tell you is if the issue is the LabCorp test or the test facility... but something with these tests are definitely wrong. I would strongly encourage you to go take the PETH again somewhere else (even if they use LabCorp as the backend) and compare the results. Depending on the timelines for doing so you can make the argument that it could have naturally fallen but if you are taking it close together - ideally the same day - it is pretty hard to argue something is not wrong wit the test. Of note there are also blood-drawn (e.g. using a vial vs a finger prick card) that also have produced good results for us while failing the LabCorp test. Request-a-Test as example does this test. PM me if you need more info or if you happen to be failing the test in Dallas as I would like to compare notes with you. I would also be interested in if you take the LabCorp test somewhere else and pass it on the same/next day if you have to take the test again.