Learn to Read Your Lab Result... Video Transcript

Participants

, Gwen L. Nichols MD

Summary

Doctors will follow your progress in fighting CML through repeat blood tests. Some of these tests will be familiar, but some of the tests, important in tracking CML, are very specialized.

Webcast Transcript

Doctors will follow your progress in fighting CML through repeat blood tests. Some of these tests will be familiar, like the ones you are probably familiar with from routine physical exams. But some of the tests important in tracking CML are very specialized.

One set of those tests are used to look specifically for the abnormal white blood cells that occur in CML. There are three basic types of these tests: a cytogenetic test; a florescence in situ hybridization test, which we call FISH; and something called a polymerase chain reaction test, or PCR test. Doctors sometimes refer to it as a molecular test.

In cytogenetic testing, the technicians will prepare a sample of twenty white blood cells at a particular stage of their life cycle in which chromosomes are visible under a microscope. The technicians then count how many of those twenty cells show a chromosomal abnormality that characterizes CML.

The FISH test is more sensitive. It can detect much more subtle indicators. Instead of looking at just 20 cells, with this test, the lab samples hundreds or thousands of cells for the CML abnormality. The FISH test results are usually a sentence that describes the results, like "Number of cells analyzed 500. Percent of normal cells 2.5 percent. Percent of clonally abnormal cells 97.5 percent." So the number you'd enter here is "2.5 percent."

The most sensitive test for CML is the PCR test, which looks for the abnormal gene that causes CML. It can spot one abnormal CML cell among a million normal white blood cells. Doctors hope that following treatment, this sensitive test finds no abnormal white blood cells. That's leads to a lab report of "negative."