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Cancer: Prostate Message Board

Cancer: Prostate Board Index

[QUOTE=Kirkwood;4760003]...for me was 0.01. I was just wondering if anyone knows what the lower limit is. I was told that any readings below that level, are just stated at 0.01 because of the inability to be calculated accuratly below that.

I have found a lot of articles that discuss this issue, but no solid and respected conclusions.



The limits of readings in PSA tests are dependent on the ultra-sensitive kits (assays) you used. The laboratory where I have my PSA tested since 2005 uses Abbot kits in my case, which has a range from 100ng/ml to a lower limit of 0.01 ng/ml. This makes them to report levels on the “<0.01” mark, disregarding any possible lower reading that another assay could indicate.
Abbot, Siemens, Roche, Bayer, etc., assays equally have similar kits and they all present 3rd generation kits (0.XXX) for PSA with limits from 20ng/ml to a lower limit of 0.005 ng/ml with reliable readings. They all are approved for PSA testing by NCCN, and follow the “Laboratory Medicine Practice Guidelines”, however, those lower limits varies among the kits used for the test (on average of 0.005 between kits) and, most importantly, the low variations could be an effect of the person biorhythm on the day it draw blood.

I read of a case where the same patient took the test every day of one calendar month using the same kit and they found different readings (up and down) in a range of 0.10 between some of the days of the test. Prostate trauma, infection or inflammation was ruled out and the value could well mean that periodical PSA tests are actually substantially lower or higher even in the sensitivity of the two decimal places (0.XX).

Discussions have occurred in regards to a defined detection limit (DDL) which is followed by the majority of PCa doctors as 0.01. Many even take a DDL=0.1.
In my view, the important is to have the periodical PSA test done at the same laboratory, trust it and disregard those lower readings from the third place decimal (0.XXX) which causes “PSA Anxiety” and that could lead to an erroneous judgement and diagnosis. Recurrence can be indicative on those tests but it is not generally used in practice.

PSA=0.01 after RRP is considered a successful result from treatment. It couldn't be better.

You can read about these test kits and the controversy of the third generation assays in PSA practical use, in the net. Just type the name.

Baptista ;)

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