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What Defines Undetectable PSA?

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Posted 7/17/2009 10:00 PM (GMT 0)
I had my 6 week post-surgery PSA test yesterday.

0.004 ng/ml.

In the words of my daughter...  WHEEEEEEEEEE-HOOOOOOOOOOOOOO!!!

So, what level actually defines undetectable?  I've seen a variety of answers.

And honestly, I thought that 0.05 was the lowest the test would go...

What's the story?

Posted 7/17/2009 10:10 PM (GMT 0)
Congrats on a big major zero.

The answer to your questions varies much. I think the official answer is anything less than <.10.
Some people's come back to the 1/100th, i.e. .05 and your's came back to the 1/1000th, i.e. .004.

I have read lots of sources that feel that the ultra sensitive tests aren't all that accurate once you get into that range, and even day to day, there would be up and done flucuations.

The important thing, is you have a zero and welcome to the club. Hope you stay there for many years.

david in sc
Posted 7/17/2009 10:13 PM (GMT 0)
I believe the "official" answer (so to speak) is 0.1. Purgatory's point is well taken, which I will paraphrase to say that anything below 0.1 is mostly laboratory noise.
Posted 7/17/2009 10:14 PM (GMT 0)
Hey, as long as it stays below 0.1, that lab can be as noisy as it wants...

Happy to be a big, fat ZERO (reminds me of high school...)
Posted 7/17/2009 10:16 PM (GMT 0)
Congrats on the big zero.  Wishing you a lifetime of them
Posted 7/18/2009 4:54 AM (GMT 0)
Hey Psaltiri,

Great news on the undetectable! May you have many, many more!

Kind regards,

Barry
Posted 7/18/2009 5:03 AM (GMT 0)
Good One Psaltiri ! yeah yeah yeah yeah yeah yeah yeah yeah yeah yeah yeah yeah yeah
Posted 7/18/2009 10:06 AM (GMT 0)
Generation 3 testing came into use just before the year 2000. The test has a claimed lower detection limit of .003ng/mL. So strictly speaking if your PSA were below .003 it would not be detected therefore is "undetectable". The problem is that if you tested that same sample a number of times the results would vary considerably at the three decimal place level (it could easily register .003 on one run and .006 on another....... a 100% variation), so the test is said to have a functional sensitivity of .01ng/mL....ie. you are undetectable if you register less than .01 on Gen 3 equipment. This can be further complicated if the lab is using generation 2 equipment ( developed mid 90s) which has 1/10th the sensitivity of the later equipment (ie. a lower detection limit of .03ng/mL). Generation 2 has a functional sensitivity of 0.1ng/mL so if you are below this on that equipment you are "undetectable". I assume that to cover all bases it is acknowledged that you are undetectable if your PSA registers below 0.1.
Bit of reading here (under "what is an ultrasensitive PSA assay" ):
www.prostate-cancer.org/education/preclin/McDermed_Using_PSA_Intelligently2.html
By the way, after all that congratulations on being "undetectable"
yeah
Bill
Posted 7/18/2009 10:34 AM (GMT 0)
A very good result, Psaltiri.

You ask what counts as undetectable. Speaking as a chemist who was involved with all sorts of analytical tests (but never with the determination of PSA levels), the limits of a test depends on the method of analysis that is used and the laboratory carrying out the test. As time goes on, new and more sensitive methods become available, but these have to be validated (ie, proved to be reliable) before use. The results from the validation show, amongst other things, how much statistical variability there is in the results from the repeated analysis of a single sample and therefore how much confidence can be placed in any particular finding. As you might expect, the lower the measured concentration, the greater the variability - what CapnLarry refers to as "laboratory noise".

The possible need to purchase new equipment for the more sensitive methods, plus the requirement for the validation of the new methods, means that it can take a long time for newer methods to become widely used so you have different laboratories reporting in different ways.

As I say, I don't have any experience of the PSA methods so I can't comment on what methods are available for its determination and how accurate and precise the different methods are. However, as David and CapnLarry say, while extremely assuring to get a very low PSA result what is more important is to get a result that has no clinical significance, and nowadays that is taken to be below 0.1 ng/mL for PSA.

Also, bear in mind that below 0.1 ng/mL is exactly what it says - the PSA level is somewhere below 0.1 ng/mL. It could be a hundred times lower than this but the test is not sensitive enough to report the result other than as being below 0.1 ng/mL. But you can be confident that it is less than 0.1 ng/mL.

Roger
Posted 7/18/2009 7:03 PM (GMT 0)
welcome to the club my friend. I pray you will have many years of zero's. Enjoy life

peace and love
dale
Posted 7/20/2009 2:15 PM (GMT 0)

Psaltiri said...
So, what level actually defines undetectable?  I've seen a variety of answers.

What's the story?

I've asked my Surgeon / Urologist this same question several times and the answer he consistently gives me is that he and the hospital - Northwestern Memorial Hospital in Chicago - do not report beyond 0.0 - and that  they consider that level "undetectable."  Remember that different laboratories may report different testing results for the same sample and that what you may read from one person posting test results and sensitivity levels can be an 'apples to oranges' comparison with your situation.  I still wonder though . . .

Posted 7/21/2009 5:48 AM (GMT 0)
Thanks all for the feedback. I'm happy it's low, and am not going to worry overmuch about the noise.

We're getting ready to start hormone therapy in early September, and will add adjuvant radiation probably in November. In the meantime, I'm hoping to take a jaunt out to the Netherlands to have the Combidex test. I just don't want to give this cancer any footing.

I'm even starting to see some real progress in the incontinence! The muscles are starting to "just work", and they even seem to work better if I don't try to "make them work", if that makes any sense...

I keep all in this "reluctant brotherhood" in my thoughts and prayers every day.

Be well.
Posted 7/21/2009 6:53 AM (GMT 0)

Psaltiri said...
I'm even starting to see some real progress in the incontinence! The muscles are starting to "just work", and they even seem to work better if I don't try to "make them work", if that makes any sense...


I know what you mean because I'm finding the same. I thought I was going to have to walk around with my pelvic floor muscles squeezed hard for the rest of my life but, instead, I'm finding they can be relaxed and urine is still retained.

All the best, Roger
Posted 7/21/2009 2:12 PM (GMT 0)
Since everyone is being supportive and telling you not to worry I thought I would take the other approach. Given the rate of medical progress, when you are 80 years old your PSA is going to come back at 0.0000004 and you are STILL not going to know whether you should worry about it
Posted 7/21/2009 4:32 PM (GMT 0)
Maybe so, geezer99, maybe so. But that's 38 years away, and PSA tests are not the only thing that will improve with our medical progress. There will be other advances as well, perhaps including full prevention, and even out-and-out cure...

But I'm sure I'll find other things to obsess about during that time... ;-)
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