Labcorp uPSA 0.014 versus < 0.006 issue revisited

TL;DR version is: I got great news on this latest test--back down from 0.014 to < 0.006. And I am suspicious of LabCorp’s reporting standardizations around the lower end of the testing limits, as verified by many others and one oncologist.

First off, this commentary is around one specific issue: my experience at the very bottom end of the Labcorp testing threshold. It is not meant as a commentary on the sensitive issues of uPSA testing specifically, people's philosophies around uPSA testing, the benefits of uPSA testing, nor the drawbacks of uPSA testing
I posted a few months ago about my results from the Labcorp uPSA and have made comments since then around the issue. I had received three undetectable Labcorp uPSA readings at < 0.006 (and one Quest < 0.02, which was my first post-surgery test) since my surgery in 11/23. Then, in 1/25, I got a 0.014 reading with no less than sign. As with most men, getting the first reported detectable uPSA reading was a shock. Yesterday, my first test since the 0.014, I went back down to < 0.006.

I’m aware of the risk of uPSAs “bouncing around” and knew I still was at a very low level. Over time, one thing I noticed, including in this forum, was the number of times the 0.014 number popped up. 0.014, with and without the less than sign, was frequent in many posts. I then started noticing how many men reported a detectable 0.014 but then went right back down to < 0.006 on the next test. I spoke to seven different men on different forums that all had been < 0.006 before going to 0.014 and then went right back to < 0.006 on the next test. The oncologist of one of these men even told him, “I’ve seen your 0.014 MANY times and almost always it has gone back to < 0.006 on the next text. Don’t worry about this blip.” This was more specific commentary from the doctor than just, “Oh, you are at a low uPSA. Don’t worry about it.” Three of the men were in locations nearby me and most certainly had their tests done at the main Houston facility. Some of the men were post RP, some post radiation, and some on ADT, so it was a wide net. Finally, I know about the issue discussed about 4-5 years ago regarding Labcorp switching their lower reporting threshold from < 0.006 up to < 0.014 then back down to < 0.006. That created confusion for people at that time; this could be a holdover from that.

So, what does this mean? First, it IS possible I had a real bounce to 0.014, which is the limit of quantitation of the test. But, I find this unlikely. Given the fact that this particular test has a Limit of Blank of 0.006, a Limit of Detection of 0.01, and a Limit of Quantitation of of 0.014, and given what happened in 2020-2021 with the confusion around 0.006 and 0.014, I suspect something goes on at Labcorp between offices and/or technicians and/or software where something gets reported “wrong/differently” at times, where the limits of quantitation and blank somehow get switched or confused.

I posed the question to a testing professionals group on Reddit and most of the responses believed that the number translation from the machine to my patient portal was automatic on a test like this, with no chance for a transcription error, but I’m not sure I buy it. There has to be some kind of software error or switch the tech is flipping that is causing this problem for guys. I’d also comment that in recent years, I don’t see many 0.008s or 0.011s etc, i.e. something between the limit of blank and the limit of quantitation, reported on the Labcorp assay by folks on forums, although they must exist. In the period of the 2010s, these numbers between 0.006 and 0.014 seemed to be reported more often.

My guess in all of this is that Labcorp is huge, has a lot of employees, lots of offices, lots of testing equipment, lots of supervisors, so there is much opportunity for this type of thing to happen. Furthermore, this is only an important issue (to me) at the lowest levels, near the various testing “limits”. If you are a 0.058 versus a 0.053, you probably aren’t as sensitive as someone waiting on their first spike, where < 0.006 versus 0.014 is earth-moving.

In any event, I wanted to pass this along in case others have to deal with this specific issue.