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Comparison of PSA test results from Quest and Labcorp
Prostate Cancer | Last Active: Jan 11 2:23pm | Replies (15)Comment receiving replies
I’m frustrated because I was careful to use same lab for follow up PSA (it’s been almost six months since surgery). I noticed they used a different test methodology. Why would same lab used a different test methodology? I’m now left wondering if it’s worth it to immediately retake and then specifically to use same method as the initial PSA.
Logically, this isn’t a big deal unless PSA score is at that >.1 threshold. However, just thought funny even going to same lab still didn’t eliminate variation.
Replies to "I’m frustrated because I was careful to use same lab for follow up PSA (it’s been..."
@ctnomad This does seems odd, to say the least. Only thing I can think of to explain this is that, as Jeff suggested, one test might have been the normal test and the other an ultra sensitive test. Those use different instruments and protocols.
How different/close were your results?
If they were within 10% of each other, I might be disinclined to retest immediately.
Having said that, I think that one’s anxiety level is a significant factor, regardless of the numbers. When my normal PSA test in June 2025 came back at 0.11 (had been below 0.1 for ten years), I was pretty anxious about that result, whereas my urologist thought it was just lab variation and was unconcerned. I went back to Quest a few days later to retest (got my PCP to order the test), and got a value of 0.12. Those results were close enough to rule against my urologist’s lab variation hypothesis.
Another consideration: if the results were close to 0.1 (threshold of detection), as in my case, that might be reason to retest. My normal PSA test by Quest in Sept 2025 yielded 0.11—just over the threshold of detection, just like back in June. But the same-day ultra sensitive PSA test by Labcorp came yielded 0.094—just under the threshold of detection. If I had done only the ultra sensitive Labcorp test back in June, and gotten that same result (below 0.1), I doubt that my urologist would have taken any further action for at least 3 months or more. My diagnosis of a local recurrence may have been delayed, along with treatment for the recurrence.
My bottom line thought: PSA anxiety is a real thing. If it puts your mind at ease to retest, then go ahead and do it. Even if you have to pay out of pocket, it’s not all that expensive.
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@ctnomad
Did you really mean to say < .1? You used the greater than a sign which makes it look like your PSA is above .1.
What do you mean by test methodology? Did they do an ultra sensitive test instead of a test that results in one decimal point?
If the Test result is < .1 It is considered undetectable so it’s not something to really be greatly concerned about.