CGA (Chromogranin) results from different labs
Does anyone know how much CGA results can vary from lab to lab. Following are the last four CGA results for my wife: 75 (11/16 @ Mayo Rochester); 125 (5/17 @ Mayo Rochester); 411 (10/17 @ UW Health in Madison, WI) and 478 at a local clinic in Neenah, WI. My wife started on Octreotide LAR 30 in late October 2017.
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@tomewilson This is a good question, Tom. Does anyone have any information about the variance of CGA results from lab to lab?
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My husband said getting that test done at different labs can throw off the results. It’s just the way the different labs and their systems run it. I hope that makes sense. My husband had it done at U-Penn and it was 23,000 and then again a month later at a different lab in NJ and it was 13,000. That’s what his oncologist told him, he also said that they want him to get the blood work done at their lab all the time so it’s ran the same way. I hope this helps you understand. If your still concerned ask her dr to explain it to you.
Tom, I’m not sure what you mean by “CgA results can vary from lab to lab”. However, different labs perform different tests to measure for CgA; consequently, they have different reference ranges for what is normal. Normal range at Mayo’s lab is less than 93 (but back in 2010 when I first had this test done at Mayo normal was less than 225…not sure when they changed to a different method of testing) University of Iowa sends theirs to ARUP with a normal range of 0-95, my local oncologist sends to Quest whose normal is 1.9-15.0. If theCgA is performed by different labs which use different methods of testing it’s like comparing apples and oranges. Bottom line is know what the normal range is and that will determine if you can compare results. Hope this makes sense.
@jls77 and @smdoonan
Thank you for your input in describing how different labs use different testing methods. The CgA has always been a bit confusing to me as well.
I agree with you. I wonder about the quality control within labs even if their range is different. How good of job are they doing. As you may know, Dr. Woltering sends his to ISI – he warns patients not to use ‘Bob’s lab’.
Hmmm, that is interesting. Has your wife ever seen Dr. Woltering?
I don’t know the answer to that question but any respected lab needs to follow certain procedures and certifications to ensure quality control. If you question the validity of a test result, the test should either be repeated at that time or in a couple of weeks to a month. For pancreastatin and Neurokinin A, ISI is the place to have it sent out to. Other carcinoid testing can be sent elsewhere, just try to have it done consistently at the same lab.
Your last sentence about consistently done at the same lab is probably the important factor. While I go to Univ. of Michigan, my blood tests are always read at Mayo in Rochester, which gives me consistent results.
Here is an article from Mayo regarding this test, https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/34641.
One important thing to consider is the section titled, “Cautions.” There are many factors, other than active carcinoid activity that can cause an elevation in the CgA level, including meds and other health problems, such as heart, renal, liver problems, etc.
Thank you. Very good information on CG-A