Guest guest Posted September 30, 2008 Report Share Posted September 30, 2008 Larry wrote: > Actually, forgive me. I just reread your post and you do list > the immunoassay as different. I also had 2 different > immunoassays, and found out that the average difference > between them was approx. 23%. If you do some searches, you > can find the material I referred to and perhaps find out more. It looks like Larry actually did some research before posting whereas I, following the true Internet tradition, spoke from ignorance. I take back what I said in my posting that the differences only appear after the decimal point. I was wrong. Following Larry's advice, I did a search on Google for the terms: psa immunoassay difference The top result was: http://www.clinchem.org/cgi/content/full/43/12/2426 The research published on that web page indicated that, when the study was done in 1996, there was indeed a great deal of variability in the different methods. Variability existed between different tests using different methods, and between different tests using the same method, though the different method variablility was much greater. There was variability between total PSA test results, and even greater variability between percentage free PSA test results. Precision of the results was worst for very low PSA values, but was pretty bad even for higher values. The URL above provides the summarized data in tables and graphs, together with some analysis. I don't know if the situation has improved since 1996. ---- In light of this, I retract the comments I made in my earlier response to Larry's question about variability in PSA tests. However I still stand by the advice to 1) seek professional advice and 2) consider primary treatment now. If the 16.6 PSA value that Larry received is off by as much as 30%, then his true PSA at the time was likely somewhere in the range between 12 - 21. It's still enough to put him above the " low risk " category, as is his Gleason 7 (assuming that it's accurate) and his 9 of 12 cores positive (assuming that's accurate). So there are several independent measures, each of which indicates that his risk of death from PCA is not " low " . A doctor should be consulted, not an Internet bumbler like myself. But I suspect the doctor will say that it's time to get treatment. Alan Quote Link to comment Share on other sites More sharing options...
Guest guest Posted September 30, 2008 Report Share Posted September 30, 2008 Alan Meyer wrote: .... > In light of this, I retract the comments I made in my earlier > response to Larry's question about variability in PSA tests. .... > If the 16.6 PSA value that Larry received is off by ... .... Oops. I should have said " Jeff " , not " Larry " in the above sentences. Alan Quote Link to comment Share on other sites More sharing options...
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