In reviewing methodology of a manuscript, I found out that CA125 levels in ovarian cyst fluids were measured using an ELISA kit. In the kit manual, it says that this kit is used for measuring CA125 in serum or plasma. Is this CA125 measurement valid?
Hi Soroush,
If the kit is meant for serum/plasma, it is the responsibility of the scientist to ensure there is parallelism between any other sample type before using the data from the kit for interpretation and decision making. One needs to conduct experiments to prove that cystic fluid has no matrix effects which will skew the results one way or the other. If you need more details on how some of these experiments can be conducted, feel free to reach out and I can point you towards some documents.
Thank you Nikunj Tanna
It would be very helpful if you send these documents.
Do we have to explain the validity of our measurement or is the use of ELISA for cyst fluid analysis common? (or is there ELSIA kits specifically designed for cyst fluid?)
It seems that other articles also used methods not designed for cyst fluid analysis in their study. One example is (Levy A, Popovici T, Bories PN. Tumor markers in pancreatic cystic fluids for diagnosis of malignant cysts. Int J Biol Markers. 2017 Jul 24;32(3):e291-e296) which used Cobas E analyzer (Roche Diagnostics) that, according to the manual, is not designed for cyst fluid analysis.
Soroush Dianaty , those labs should have (hopefully) performed some experiments to ensure that when they spike the same amount of analyte in plasma and cystic fluid, they get the same read out from the instrument/kit.
These 2 papers discuss what is parallelism and matrix effects, how to perform experiments to detect it and how to resolve it. Hope it helps.
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