PSA Result Help: What's the difference between PSA and Free PSA?

It is another determining factor in trying to figure out if you have Prostate Cancer, that ship has sailed. I don't really think it's too important in your case.

From the Prostate Cancer Free.org website..
https://www.prostatecancerfree.org/prostate-specific-antigen-psa/
Then about 3/4 down the page...

What is “Free PSA?”
Free PSA is a diagnostics test separate and unique from the standard PSA Blood Test. Total PSA is the sum of the free and the bound forms. Most PSA binds to other proteins in the blood. The remaining unattached PSA is named “free” PSA. Men with a lower percentage of free PSA have a higher risk for prostate cancer. For example, a man whose total PSA is 6.0 ng/ml with a 10 percent free PSA has a higher likelihood of having prostate cancer than another patient whose total PSA also is 6.0 ng/ml but with 35 percent free PSA. Therefore a high free PSA percentage is good. Free PSA is not used to monitor results after treatment only to evaluate risk before diagnosis. The free PSA test is particularly helpful in situations where a biopsy is negative but the PSA is slightly high. If there is a low free PSA, another biopsy 6-12 months later is usually recommended. If it is high, then a longer wait is usually recommended.

The free PSA test is a road sign to help determine whether further work-up and follow-up is necessary. A high free PSA does not guarantee that a person is free of prostate cancer. In some cases, a biopsy of a nodule will turn up prostate cancer despite a low overall total PSA and a high level free PSA. The total PSA is what is measured with the standard PSA test.

Edit to add: If Prostate Specific Antigen 0.086 <4.0 ug/L is your PSA in your surgical path report, you should keep in mind that PSA has something like a 2-3 day half life in the blood. You can actually make up a spread sheet to see what your progress should look like in estimated terms.
Yours would look something like this...assuming surgery yesterday. This is why a lot of docs say wait three mos before the next PSA. I was trying to get back to work and needed to get to <.2 so I followed it a little closer. Thee are some great posts here regarding PSA info if you look around some more.

Date Expected PSA
11/21/22 0.400
11/24/22 0.200
11/27/22 0.100
11/30/22 0.050
12/03/22 0.025
12/06/22 0.013
12/09/22 0.006

Hi @web265

Sorry, I forgot to mention that my surgery was done on 15-Feb-2022. And PSA test was done after six weeks, and it was 0.017. After 4 Months, it came to 0.075, and I went again on 20-Oct-2022, which came to 0.086.

Well the free PSA definition is still the same. I'd guess you are in the not so fun waiting game for the next test?

Is there other reasons ones Free PSA would be low?
My husbands PSA is 8.1 and Free PSA was 6%
He is being sent for an ultrasound and possible biopsy. He has a pacemaker so MRI isn’t an option right now I don’t believe. Waiting for call next week to find out more but I’m curious if there are other reasons a Free PSA would be low?

Since you're not getting any better answers as of today....

I don't know a great deal about it, and I'm no doc....and...I don't think it's definitive but I believe low free PSA can be considered a marker for Pca. I also see in searching that 6 % is considered fairly low and may be used in the decision process as an indicator tipping the scale toward a biopsy.

The PSA range is kind of age dependent, meaning the older you get the higher normal PSA can be, but with a PSA of 8, Cancer.org with suggest something like a 25% chance of cancer, over ten is more like a 50% + chance. Given the lower free PSA, that could push the doc toward a biopsy suggestion.

Age and other health factors, i.e. rate of increase of PSA could, of course, play into this decision as well.

In answer to your direct question, I don't know what else could cause that. In searching around it seems the the correlation is the factor the docs use.

Best of luck and good luck to you and your husband!

They are sending him to a specialist for I believe ultrasound/biopsy on August 15 but I was just wondering if there were other things that could make that psa range that low. I do thank you for your reply!

@lorkem258, here is a good explanation from Harvard Medicine:
- What is the difference between PSA and free PSA? Do I need to have both tests? https://www.health.harvard.edu/blog/what-is-the-difference-between-psa-and-free-psa-20091001114

Yes, I do believe I understand now. I was just hoping there were more reasons for the free psa to be so low percentage. Hoping for the best after his biopsy Wednesday. Thank you for the links.

I'll be interested to hear what you learn after the biopsy.

Thank you Colleen. Informative read on psa free.