Lowest PSA that Mayo Rochester measures?

The lowest PSA value my husband has ever gotten is < .10, which is always labelled "undetectable." Our local lab does report values lower than that for the PSA. When we asked the Mayo providers about this, we were told that the Mayo lab doesn't record values below .10 for the PSA, and that anything below .10 is considered undetectable. Note that this is not necessarily identical to a zero value.

Difference is super sensitive test vs normal test

My first test was < 0.01. My second test will be in the next couple of weeks.🙏

I'm live in Fairfax VA and the hospital lab measures PSA < 0.100 as the lowest. My doctor also say < 0.100 is "undetectable". However, I have used other labs to test my PSA and that lab (which will not be named) measured PSA as low as 0.01. But there was a disclaimer that the test could be inaccurate +-20%. I used to beat myself up and down about what "undetectable" really means. To be clear, I still have my prostate because I am De Novo stage 4. But as a point of reference, when first diagnosed, my Radiologist Oncologist said I would never get to undetectable because I have a prostate. Well, she was wrong. So, in summary, I am not sure some of these more sensitive tests are as accurate if they state a disclaimer that your results might be off +- 20%. I am grateful my PSA continues to come back < 0.100. God Bless everyone and keep fighting.

My understanding is that regular PSA testing sensitivity reports less than .1 as undetectable after RP.

uPSA testing at Quest reports less than .02 as undetectable. Johns Hopkins lab reports uPSA less than .03 as undetectable.

And I've seen lower parameters posted from others.

Not at all clear to me why some Rad Oncs/Med Oncs use PSA vs uPSA tests.

I know that I will "lose my sh*t" if/when my PSA rises above .02, but is still less than .1

And a couple of friends post salvage radiation are being tested using regular PSA test.

There has been some thought that the Ultrasensitve testing can result in unnecessary anxiety when very low levels change or vacillate. 🤔

ultrasensitive PSA (uPSA) Roche assay @ labcorp goes down to < .006, but I think it measures in increments of .004, so < .006, .008, .012, .016, .020, ....

The progress of science is uneven. It seems the treatment and the gathering of statistics have to catch up with the testing and scanning.

I think your radiation oncologist was suggesting that your PSA cannot be undetectable when not being treatment with hormone treatment. If the patient has had a prostatectomy they can have a undetectable PSA after successful treatment whereas a patient who chooses the radiation path will never be undetectable (assuming they are not being treated by hormone treatment).

I have been treated by Mayo and several other cancer centers. I believe Mayo chooses to use the less precise PSA test because they believe that discerning recurrence with low levels can be unnecessarily stressful for the patient without a real value. Treatments do not change when patients PSA goes up from .02 to .03 as an example. But a patient's anxiety certainly does. PSA is more volitile at very low levels. For instance, my PSA once increased from < .015 to .09 and then went down to < .015 months later.

Velohomme,

Thanks very much for this succinct explanation. Just what I was looking for.

Mayo’s protocol for this measurement now seems quite reasonable to me. Thanks again!

@jamesharrison,
I am a Mayo patient and are having my PSA checked there every 3 months after radiation therapy. I was told the .02 is the level it is deemed undetecable.

Unless you had RP that level is rarely seen. Your prostrate (if you still have one) will make PSA and that is normal to have it. Many things can cause your PSA to go up or down NOT just cancer.

My PSA was 3.75 when I started proton radiation treatments. After 3 months went to 1.90. 3 monts later .90. Then my last one was .60. I was told thae goal was below 1. So I am already there.

What my EP and radiologist/oncologist now is when you have a significant increase in PSA levels to see what is causing it. Again many things can cause it to go up like bike riding, infrections, irritations to prostrate. So a slight up and down is expected it is the continuing climb each time that is considered a concern.