PSA Test Equipment Sensitivity

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Sharp18
Regular Member


Date Joined Mar 2010
Total Posts : 78
   Posted 4/15/2010 10:34 AM (GMT -6)   

When reviewing PSA blood test results what does symbol “<” indicate?  Is it the equiment sensitivity of 0.04?

 

For example PSA <0.04 test indicates that equipment could not detect any PSA and, therefore indicates that it is only able to detect PSA above 0.04.  Does that mean that in this specific example PSA actual value may be anywhere from 0.00 to 0.04?


Casey59
Veteran Member


Date Joined Sep 2009
Total Posts : 3172
   Posted 4/15/2010 10:46 AM (GMT -6)   
You've got the idea.

The "<" is the mathematical symbol for "less than"

The Lower Detection Limit (LDL) of the test you described was 0.04 ng/mL...so you are exactly right that the actual PSA value was somewhere between the unobtainable value of "zero" and 0.04 ng/mL.
 
The test method used simply cannot detect levels of PSA below the LDL.
 
A "standard" PSA test checks down to 0.1 ng/mL.  There are a variety of "ultra-sensitive" PSA tests which have various lower detection limits; most commonly 0.03 ng/mL. 
 

IdahoSurvivor
Veteran Member


Date Joined Aug 2007
Total Posts : 1015
   Posted 4/15/2010 10:46 AM (GMT -6)   
"<" this symbol means "less than," so <.04 means that the PSA reading was less than .04 mgl.

And, it is true (according to physicians I've talked to) that even a woman can have a very small, but detectable PSA reading at these sensitivity levels.

Barry
Surgery: Da Vinci; July 31, 2007; 54 on surgery day;
Pathology: PSA: 4.3; Gleason: 3+3=6; T2a; Confined to Prostate;
Post RP PSAs: 09/'07 <0.04; 12/'07 <0.04; 03/'08 <0.04;
06/'08 <0.04; 12/'08 <0.04; 06/'09 =0.06; 09/'09 <0.04; 12/'09 =0.05;
Latest PSA 3/'10 <0.04


Purgatory
Elite Member


Date Joined Oct 2008
Total Posts : 25393
   Posted 4/15/2010 2:09 PM (GMT -6)   
RIght on the money, that is exactly what it means
Age: 57, 56 dx, PSA: 7/07 5.8, 7/08 12.3, 9/08 14.5, 10/08 16.3
3rd Biopsy: 9/08 - 7/7 Positive, 40-90% Cancer, Gleason 4+3
Open RP: 11/08, Rht nerves saved, 4 days in hospt, on catheters for 63 days, 5th one out 1/09
Path Rpt: Gleason 3+4, pT2c, 42g, 20% cancer, 1 pos margin
Incontinence:  1 Month     ED:  Non issue at any point post surgery, no problem post SRT
Post Surgery  PSA: 2/09 .05,5/09 .1, 6/09 .11. 8/09 .16
Post SRT PSA: 1/10 .12, 4/8 .04
Latest: 7/9 met 2 rad. oncl, 7/9 cath #6 - blockage, 8/9 2nd corr surgery, 8/9 cath #7 out 38 days, 9/9 - met 3rd rad. oncl., mapped  9/9, 10/1 - 3rd corr. surgery - SP cath/hard dialation, 10/5 - 11/27 IMRT SRT 39 sess/72 gys ,cath #8 33 days, Cath #9 35 days, 12/7 - Cath #10 43 days, 1/19 - Corr Surgery #4,  Caths #11 and #12  same time, 2/8-Cath #11 out - 21 days, 3/2- Cath #12 out - 41 days, 3/2- Corr Surgery #5, 3/6 Cath #13 out - 4 days, Cath #14 out - 27 days, Cath #15 - 3/29


Radical
Veteran Member


Date Joined Mar 2009
Total Posts : 739
   Posted 4/15/2010 3:54 PM (GMT -6)   
Dont forget some machines, depending on which one your pathology people are using,  can only report as low as 0.04 or 0.03.  Hopefully BillyMac will chime in here, he has alot of experience on this subject.
Age 51yrs
6 out of 8 cores positive 3 X 60% / 3 X 10%
PSA 4 Gleason Score 3+4=7 Stage T1c
Robotic Surgery 24/12/08
Upgrade Gleason Score 4+3=7 Gleason Differential 60%/40%
Stage T2c Three small foci total volume <10%
Neg Margins and Nodes
Nil - Extraprostatic Extentions
Dry less than 1 week. ED- okay with Meds.
PSA at 12mths no change remains 0.03
"Everyday in Everyway I get better"


BillyMac
Veteran Member


Date Joined Feb 2008
Total Posts : 1858
   Posted 4/15/2010 11:09 PM (GMT -6)   
There are 3 generations of test equipment although I doubt that the original is in use much. Generation 1 which became available in the late '80s had a lowest detection limit of 0.3 ng/mL so if PSA was not detected you were <0.3 (less than 0.3). In the mid '90s generation 2 equipment was developed which was 10 times more sensitive. It had a lower limit of detection of 0.03 ng/mL. If PSA was not detected with Gen2 you were <0.03 (less than 0.03). In the late '90s Generation 3 equipment was developed. It is 100 times more sensitive than Gen1 and 10 times more sensitive that Gen2. Its lowest level of detection is 0.003 ng/mL. If PSA is not detected with Gen 3 you are <0.003 (less than 0.003). But at such infinitesimal levels the results can and do vary even on the same sample. To get an accurate read of your PSA at such low levels the original would be divided and tested a number of times and an average calculated. For this reason a Gen 3 undetectable result is usually written up as <0.01 (less than 0.01 Ng/mL) . I actually would not sweat the < symbol too much. If you have a result of <0.01 and the next result is 0.01 the likelihood is a slack report (some twit tech does not understand the significance of the < symbol) rather than an increase in your PSA. I believe that the reason some are reported as <0.04 undetectable while others report <0.03 undetectable is different manufacturers equipment have a slight difference in the stated lowest level of detection .
The section "what is ultrasensitive PSA" in this link is worth a read:

www.prostate-cancer.org/education/preclin/McDermed_Using_PSA_Intelligently2.html

Bill

Post Edited (BillyMac) : 4/15/2010 10:21:25 PM (GMT-6)

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