I’m putting this subject out here for anyone who wants to share some myths and facts about our biggest testing indicator PSA.
I’ll start.
The clinic accidentally took two psa tests from me within an hour of each other.
The first one read: 11.814
Second one read: 11. 327
(I found this interesting)
I also read that both masturbating/sex and exercise beforehand alters results. Any truth to this?
Yes, there is truth about that. Confirmed also by trials (but if I remember correctly, trials involving healthy adults).
The difference between the 2 tests is about 4%, well within the 20% nominal max deviation. But, there is more to it. You know the time lapse between the 2 draws (1 hour). What you don't know is when they were analyzed. PSA has a half-life of 2 to 3.5 days or 48 to 84 hours. If the first sample was analyzed during the morning shift and the second was stored to wait for the afternoon shift, this 4% can be only 4 hours extra delay from blood draw to analysis for the second sample. My rule of thumb is to suspect lab error when the reported value is +/- 30% or more to the one that I have pre-estimated. Example: for my latest test I had estimated 0.012 to 0.013 and got 0.006. Trying to figure out if it is valid or an error. Complicating things is that similar discrepancy happened same time last year.
so have i understood that a PSA test gave a margin or error and or variability of 20% ! Or have I misread this ?
I done 5 years on from my initial diagnosis when (only because I’d insisted on yearly PSA test since the age of 58) when it was 0.86) my initial recall PSA was 4.15 and had CT and MRI 7 days later when they tested again and it was 3.60.
Wonder if 7 days variable of 14% is normal then ?! 2 years again after being regraded from G7 low risk to G9 high rush when on ADT I had a PSA 0.05 and retest it was back to <0.01 …. Confuseing
The 20% comes from an FDA assay-analyzer approval. To get the approval they employ (at least) 2 analyzers that have been calibrated at different times, by different operators and different batches of the assay in question and measure 10 times each a common blood sample that is usually diluted from a higher PSA content sample, so they can also check the linearity of the measurment combo. The 20 results thus obtained should fit in a 20% window satisfying set confidence levels. This is the worst case scenario and surely doesn't apply to the OPs specific case. IMO the 2 samples were measured at the same analyser and the bulk of the variance is due to the repeatability of the test. Another plausible cause, as I already wrote, is the elapsed time from each blood draw to the respective analysis not being nearly equal. Re your two queries, I would accepted14% between 7 days, but not 0.05 and retest <0.01. It shouts: "ERROR".
yes the PSA of 0.01 to 0.05 was dismissed by my oncologist yesterday as a lab mess up - quote ‘we’ve had some issues with that lab lately’ but didn’t elaborate- I’ve since stuck with my primary care physician’s labs locally - so much for using the supposed more high tech labs. But may have just been unlucky one off error
My first test in June 23 was 12.7. A repeat test in Nov 23 was 9.48. With Gleason 9 I would have expected an increase. I wasn't on any medication in this period. I did have sex and had been for a bike ride before my first test, however.
There have been studies to determine that physical exercise such as running, vigorous cycling could have effect on PSA.And the studies showed little or no effect on young men (20s year olds) but slight effect on "masters" (35+ year olds) athletes. These are older men.
It was found they could have a very small affect. And the period of time that the measurements were taken had to be within an hour after the exercise for the study, after that the effect could disapate.
It was some years ago I read about it but I came away with the feeling the PSA difference was very small, and the effect was short lived, thus the one hour draw requirement.
While these two activities were studied, other physical activities might also have similar effects. Also the study was done by a company or product maker not a full fledged research lab to that effect.
This is all from my memory but you might find it by googling.
There's the ticket..more sex to drop your PSA!! yey!!
My Facts; Trends are the thing, not singular deviations. Two tests a year are not a trend. Using different labs is fine. Ultrasensitive testing is very useful. Minor deviations can be caused by hydration variances, Justfor_ fine 20% max and PSA half-life explanations. One must know labs reportable lowest value (these do vary).
Question for thought - might varying cancer cell volume affect results?
In my over 75 tests in past ten years in many different labs across multiple US states and several countries, I have yet to experience an error.
Lucky you! In my 60 or so tests 2 confirmed errors. One +600% the other -300%.
Prior to my Dx I had several 50%+ spikes that settled back on re-test. I have always wondered were they accurate, reflecting cancer or a lab error I knew not how to prove was an error?
Errors have me asking - which values are the 'error'?
Experts highly recommend , where possible , to use the same lab .
I too have heard and read this. Suggesting some unscientific reasons supporting this.
Docs like standing orders - minimum staff time. No sending orders to different labs and receiving back.
Some Docs want us in the office to issue the order and give us the result - compensated office visits.
Docs may also get compensation from same lab.
Docs have full control - including how they report. Take "undetectable" - I have never seen this word on an actual lab report.
I do ponder, if there is a substantial difference between labs, which lab is right?
As a self-directed patient I choose when and where, what type of PSA test, and I get the results directly. I do not have to see the doc on a compensated visit just to tell me it is time to test and to receive the result.
Over six years ago I consulted with a very prominent social media doc, (one some members express great trust in, and as an expert). He recommended I return from Europe to my 'same lab' in Austin, Texas for verification of my 0.13 PSA after imaging identified five suspicious pelvic lymph nodes. Needless to say, I did not and that was the last I consulted with him.
All the best to all of us as we navigate all the disparities.
"Experts" like these have got divorced with thinking. If the scope of the PSA time series is to quantify the trend, same lab is better than match and mix, in that any systematic error is eliminated in the process. But, if the absolute PSA value is to be determined, for example when trying to compare with some published value or in general when the measurement particulars are unknown, averaging multiple labs renders better alignment than just picking one at random.
I've noticed an almost religious devotion to PSA numbers on this list. I'm not going to argue that PSA is irrelevant (of course), but regarding minuscule differences as life-threatening/changing seems kind of obsessive to me. My dad had 300+ PSA for decades (he's now 93) and my PSA has been "off the charts" for years. I've noticed that some people with low PSA numbers are riddled with cancer whereas some with higher numbers are not. Makes me suspect there are multi-factors involved. Not a great insight, I know, but I would like to see a more in-depth analysis of PSA significance. Perhaps that analysis already exists somewhere?
Some people pay their monthly electricity bill by standing order with their credit card. Others wait for the low or negative tariffs to charge their EV. There isn't right or wrong, only personal preferences. The only sure thing is that the latter save some money.
Then there are the people that want their neighbors to pay their electric bills.
Yes, I am devoted as you harshly judge but I do not track "minuscule differences". I was not properly informed prior to my Dx and we overlooked the very thing we were screening for, prostate cancer.
As I share, post my RP and salvage RT, at 0.13, imaging identified five suspicious pelvic lymph nodes: salvage ePLND confirmed six including common iliac and para-aortic.
Had I not been devoted, my cancer would have had more time and obscurity, which I dangerously and foolishly gave it before my diagnosis.
My previous urologist told me that his experience showed him that if two patients have similar tumor burden but one has a very high Psa and one has a low Psa the guy with the higher Psa usually has a longer overall survival.
That seems counterintuitive to me. Did he offer any rationale for higher psa being better?
According to the latest paper it makes sense: Stronger dimers to monomers populations leading to higher PSA but also tighter progression control.
No, not really except to say that was an observation of his in 35 years of treating Pca. Mascouche has a very interesting reply to my post that may shed some light on the subject for you.
Here is what the Perplexity AI has to say:
Question: A urologist told his prostate cancer patient that his experience showed him that if two patients have similar tumor burden but one has a very high Psa and one has a low Psa the guy with the higher Psa usually has a longer overall survival. That seems counterintuitive to me. Can you offer any rationale for higher psa being better?
Answer
The urologist's observation that patients with higher PSA levels may have longer overall survival despite similar tumor burden does seem counterintuitive at first glance. However, there are a few potential explanations for this phenomenon:
PSA Production and Tumor Differentiation
Higher PSA production may indicate better-differentiated tumors. Well-differentiated prostate cancer cells often retain more normal prostate cell functions, including PSA production. These tumors tend to be less aggressive and may have a better prognosis.
Poorly differentiated tumors, which are typically more aggressive, may produce less PSA relative to their size. This could result in a lower PSA level despite a significant tumor burden.
Treatment Response and Monitoring
Patients with higher PSA levels may be more likely to receive aggressive treatment early on, potentially improving their outcomes.
Higher PSA levels make it easier to monitor treatment response and disease progression, allowing for more timely interventions if needed.
Overall Health Considerations
PSA levels can be influenced by factors other than cancer, such as prostate inflammation or benign prostatic hyperplasia (BPH). A higher PSA in some cases might reflect these non-cancerous conditions rather than more aggressive cancer.
Patients with lower PSA levels despite significant tumor burden might have other health issues affecting their overall survival, which could explain the urologist's observation.
Interesting but I think we can rule out BPH because at the time he was referring to patients with Psa in the thousands. One in particular had a Psa of over 7000. He had RP which failed and refused radiation. Severe back pain set in several years later and scans showed cancer in bones. He got a 3 mo Lupron shot which brought Psa to 4. He got a second shot which stopped all pain and brought Psa to 1 and refused further treatment. Several years later he came back with hip pain and figured it was the cancer. Tests showed no cancer but that he needed a new hip which he got. Dr. said that is probably a one in a thousand case. He told me the guy was still farming.
Going from a PSA of 7000 to 4 in just 3 months is impressive to me. It probably indicates that he reacts really well to being castrated (or more like his cancer reacts really badly to not having access to enough testosterone).
It is still amazing that he had cancer that has metastasized to his bones and that all he needed was six months of ADT to be "apparently" cancer free. I wish we were all that lucky 
My guess is that an elevated PSA can also (and likely does) indicate a higher immune response, for whatever that's worth. My guess is that it's a double-edged sword: while an elevated immune response could help contain cancer/infection, it also could cause damage in itself. For example, it might trigger an autoimmune response. My oncologist is open to that thesis, anyway. I often wonder if I'm suffering from an autoimmune issue. Is it purely coincidental that I'm suddenly losing my hearing and having digestive issues? Certainly could be but then prostate cancer can trigger something called "Paraneoplastic Syndrome." An interesting thing for me was that my oncologist suggested this on her own, while being skeptical this was happening.
Simple, myths are 8 inches......... facts are 3 inches...
Good Luck, Good Health and Good Humor.
j-o-h-n
J-0-H-N Is the 3 inches girth ?
You got a point there.......
Good Luck, Good Health and Good Humor.
j-o-h-n
I wish i could............................mastaurbate and have sex!!!!
Yep, if you read Albins book he explains why the PSA test can give volatile results.
I suppose it depends on if you use it as a screening or a cancer progression tool though.
I certainly wouldn't be relying on a single absolute measurement. I think it's best to get a time series and draw a best fit line. I reckon that's probably a better indicator.
I always wondered how many results were actually measured too low as opposed to too high since it works both ways. Could be quite a shock if you got one measurement that was incorrectly low but followed by one that was incorrectly high! 😱
that seems to be within margin of error to me.
ejaculation will definitely change the psa. PSA is a natural substance, whose role is to make sperm available in semen. So you would expect an increase caused by ejaculation. I think the exercise one is a bit of a myth, except for extensive bike rising on a hard bike seat which might irritate the prostate
What about occasional use of non-prescription drugs like NSAID's? Does that affect PSA results? If so, how much and for how long?
My doctor had me on Dutasteride for 4 years as my PSA rose to over 5 then over 6 and 7 plus
eventually to 8.2 at which point I requested he refer me to a Urologist . His reasoning on the rise was due to my BPH -- WRONG .
What he either did'nt know or never told me . When you are on Dutastreride for an extended period -- YOU DOUBLE YOUR PSA RESULT . or even 2 1/2 times your PSA .
In summary - I have prostate cancer .
And same for finesteride or propecia. Any and I mean ANY increase in PSA while on finesteride is a RED flag to go straight to the urologist. Durasteride I would assume had similar warnings your Doctor should have known about.
There were serious "black box "warnings on the medication to the doctors, these warnings are also on periodic publications sent to doctors and hospitals.
If you were on such medications during PSA rise without referral and you have advance PC you have a winning law suit against your doctor.
Lawsuit -- Not here in Canada . Every doctor contributes too a common Insurance Fund -- Hundreds of millions in the kitty to fight lawsuits which drag out for years . They typically bury you financially .
My son is a Prof . of Law and owns his own law firm . He's been there - Done that .
At my age 84 + I'd be 6 feet under and the case would still be in the courts for years . Appeal after appeal .
I won!!! Never doubt the power of a black box warnings.
Won what - A lawsuit ?
your asking a bunch of limp dicks!
PSA Fluctuation and Zytiga
Apalutamide and rising PSA 
PSA, total 
Declining psa #8
