Lost the less than sign in PSA indicator of <0.04

I get my PSA through Quest. When I got my first results (09/2024), the Quest lab report showed a number of ".04" rather than "< .04". Coincidentally, my brother (a 30 year PC survivor) continues to get routine PSA tests annually. He happened to get a psa test from Quest at about the same time as me and his test also came by as ".04" (missing the < sign), even though his psa had be undetectable for decades. Interestingly, my next psa test from Quest 3 months later was done on a different type of machine and came back as "<.1". Then the following next 2 tests (3 & 6 months later) came back as "<.04". Long story short, while I'm not a medical professional and I don't really know, I suspect your urologist is probably correct and it's nothing to worry about yet. It certainly wasn't for me and hopefully won't be for you either. Best wishes.

It’s so low you need to wait till the next test to see what’s going on. @retiredguy is really getting to the point.

If you want more precise info talk to your doctor about the possibility of doing an ultrasensitive PSA. It reports to 3 decimal places and should do away with that gray less than area.

Similar story as retireditguy….RALP 2 years ago at UCI. I had volunteered for a surgical research study so I am under tracking for the next 20 years. They order Quest Labs (ultrasensitive) PSA test with HAMA (Human Anti-Mouse Antibodies) treatment that has consistently come back <.02

However as a pilot I need to report PSA every six months to the FAA and my FAA doctor orders standard Quest tests that come back at .04. Keep in mind Quest has like 8 different PSA tests. On occasion the staffer at the doctors office will order the wrong test and I have seen .05 or .06 which gives me a heart attack only to find out they were using a different test. Now when I go in to Quest I verify precisely what test has been ordered.

The HAMA treatment is interesting. Apparently I have been exposed to mouse crap that created antibodies in my blood that read like PSA . The HAMA test accounts for that and gives me a more accurate and lower PSA. Guess I should be happy that the mouse crap exposure did not give me hantavirus!

@joegor

I believe the number of decimal places is generated by the lab. Each lab is different. Some will go to .xxxx and others will go to .x.

@dpayton
I think you will find that almost all Labs can give you multiple decimal points. You just have to ask for The Ultrasensitive test.

@dpayton Just speaking from my own experience with LabCorp, when we initially started tracking PSA they would report to one decimal place. When I saw others talking about more precise numbers I asked my doctor about it and they started using ultrasensitive on my scripts. From then on I got my numbers reported to 3 places.

Thanks for the responses fellas. Yes I was surprised when I went to Mayo oncologist stated we only go to <.10 no need to go any lower. And Mn urology lowest is <.04. I understand that’s still very low and will find out up or down on 6/16. Good luck to you all!

Something similar happened to me. Quest ran their standard test instead of the ultrasensitive one. The standard one reported 0.04. I got very concerned. It was only a few weeks later that a health care professional pointed out the error and that the standard test only goes down to 0.04 and does not report a “

@jl99 Anything below 0.1 is generally considered clinically insignificant, meaning that the only action would be to continue monitoring. The main value of ultra sensitive PSA tests seems to be to detect upward trends below 0.1 that potentially give advance warning of a biochemical recurrence.

This year I’ve had three ultra sensitive PSA tests (Labcorp) following salvage radiation in late 2025. Sequentially, the values are 0.086, 0.113 and 0.100. The average of these values is 0.100. Ironically, going into salvage radiation, my PSA was 0.094. My urologist said it best, “The data so far indicate that your PSA is very low and stable, but we will continue with frequent monitoring.”

From numerous discussions and readings, I’ve learned that there is a lot of potential noise in those second and third decimal places. Ultra sensitive values can bounce around for reasons having nothing to do with prostate cancer. Only when there is a persistent upward trend should there be cause for concern. The trick is to convince one's anxious brain of that.

I should mention that even though my usPSA was 0.0984 just prior to salvage radiation, two prior normal PSA tests yielded 0.11 and 0.12 AND I had a palpable nodule in my prostate bed that lit up like crazy on a PSMA PET scan (unusual for low PSA, but there you have it). My PSA had been undetectable for ten years following my prostatectomy in 2015. The “glowing", palpable nodule was the primary evidence for a local recurrence, more than my PSA. The 0.11 PSA was primary data for ordering a PSMA PET scan.