In November I had a CA-125 blood test. It came back 21. The previous result was 14. I went for a retest in December and it came back 20. So it looks like it is now stable but at a different level. Keep in mind that my CA-125 was 17 when I recurred on my liver and spleen in 2008 so of course there is concern that my number was trending up - even in the normal range.
I decided to look more closely at the test results sheet because the results were reported as normal < 35 and I had thought the normal for the tests I had been having was < 21.
Here is what I found on the sheet:
" THIS TEST WAS PERFORMED USING THE BECKMAN COULTER CHEMILUMINESCENT METHOD. VALUES OBTAINED FROM DIFFERENT ASSAY METHODS CANNOT BE USED INTERCHANGEABLY. CA125 LEVELS, REGARDLESS OF VALUE, SHOULD NOT BE INTERPRETED AS ABSOLUTE EVIDENCE OF THE PRESENCE OR ABSENCE OF DISEASE.
So I went back to the report from August 2014 and sure enough the normal for the test was reported < 21.
The report said:
" THIS TEST WAS PERFORMED USING THE SIEMENS (DPC) CHEMILUMINESCENT METHOD. VALUES OBTAINED FROM DIFFERENT ASSAY METHODS CANNOT BE USED INTERCHANGEABLY. CA 125 LEVELS, REGARDLESS OF VALUE, SHOULD NOT BE INTERPRETED AS ABSOLUTE EVIDENCE OF THE PRESENCE OR ABSENCE OF DISEASE."
Ugh! "Look they went and changed the method!" Maybe that is why my CA-125 went up. The last time the method was changed the lab followed it using both tests for a few months to see how the results correlated. I was in treatment then and we were following it closely to make sure the chemo was working.
Being the research "hound" that I am I got on Google and investigated how the tests are done and what the difference was between the two methods.