Monday, February 25, 2013

The Myeloma Blood Tests

This month's myeloma blood test results moved slightly off center. Since I don't recall previously discussing all of these tests, now would probably be a good time to do that.

I do remember mentioning the free light chain tests a year or so ago, the last time they attracted this kind of attention. This time the kappa free light chain number is a shade over the top of its normal range, while the lambda and kappa-lambda ratio numbers are normal. These tests are simply measuring the concentrations in the blood of these molecules, in milligrams per liter.

The other two tests seem more subjective in nature. They involve an examination by a trained analyst of "pictures" representing the behavior of blood proteins that have been subjected to certain processes.

In serum protein electrophoresis (SPEP), blood proteins are placed at one end of a agarose gel to which an electrical current is applied. Different proteins migrate to different locations in the electrical field on the gel; if monoclonal proteins are present in significant quantities, they will show up as a dense, narrow discrete band in the gel. Of course, depending on the patient's situation, this band may be more or less dense, and more or less narrow; this is not a binary, yes/no the patient does/doesn't have myeloma test. In my case, the analyst's comment says: "A very faint discrete band."

The immunofixation electropheresis (IFE) test attempts to further validate the presence of monoclonal proteins by identifying the heavy and free light chain components involved. The electrophoresis is repeated in five "lanes" on the gel; to each lane an antibody specific to one of the three heavy chains or two light chains is applied. An antibody reaction will cause a telltale precipitation band to be left behind in that lane. A band in a heavy chain lane, paired with a band in a light chain lane, identifies a specific type of monoclonal protein. In my case, the analyst's comment says: "A very diffuse IgG Kappa band seen."

Obviously, experienced hematologists could express differences of opinion regarding the significance of such phrases as "very faint" and "very diffuse", when used in this context. For his part, my oncologist, a phlegmatic, conservative sort, seems at least outwardly to be unimpressed by all of this. We will run these tests again next month, he says, and we will see.

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