Question on First Post-Op PSA Timing

I had my open RP on 5/18 and am scheduled for a one month Uro follow up on 6/16.  The nurse gave me a lab slip to have my first post-op PSA drawn before the visit and she suggested I go the Friday before the appt. (6/10) to have the PSA done just to be sure they have the results by the time of my appointment.  My question is this: does the timing of this first PSA post-surgery matter?  If I get it done on the 10th it will have only been slightly over three weeks post surgery.  Could it yield a different result than if I waited another week until closer to the appt?(even if they don't have the result by the time of my visit) This will provide a baseline and I don't believe I will be able to get another PSA for three months so I'm looking for the best chance at obtaining the lowest possible number. Any advice appreciated. Thanks!

3 weeks is early, 6 -8weeks ist post op then every 3mos from there.

After surgery the left-over PSA in your body gets processed away and takes a certain number of days to reduce by half (like a radioactive half-life) - I think it may be 4/5 days. (I think James may know the exact number of days concerned,) Thus if you had a PSA of say 8 then it takes about a month to go down in steps: 4, 2, 1, 0.5, 0.25, 0.125, 0.06 etc, but that is very approximate. I had surgery in July and was tested in November.
Alf

I would think that PSA tests are not very expensive. I only say that because our local Sam's Club stores are doing free PSA screenings this weekend.

And I would expect that the doctor understands that it's only been 3+ weeks since your operation and that your PSA is not to zero just yet. But I think I would still go ahead and get the test because at a minimum it should show a significant downward trend to that zero mark. I would be comfortable in seeing that myself. Then just wait for another three weeks (six weeks post-op) and go get another test to see how it compares to the first one.

My (big national) lab charges $125 plus $25 blood collection fee as retail. The "negotiated" rate that the insurance pays is much less.  If you do go retail, at least they offer a small discount if you pay on-line.

My uro had mine drawn at 7 weeks post-op, but was careful to warn me that the results could be positive, and if so, would be very suspect for timing. He wants 8 weeks minimum, but there was a major holiday in the midst.

Three weeks seems a guarantee for a positive number, and an obligatory re-test. I would rather wait.

So, if I understand this half life correctly and using three days as the half life, assuming my PSA was 3.5 prior to surgery, then the time progression should yield the following:
18-May 3.5
21-May 1.75
24-May 0.875
27-May 0.4375
30-May 0.21875
2-Jun 0.109375
5-Jun 0.0546875
8-Jun 0.02734375
11-Jun 0.013671875
14-Jun 0.006835975

Which means I could very well be in the .01 range by June 11th if all went well. Seems like I should proceed and see where I'm at in comparison to this information...at least should be in the ballpark, right?