Calreticulin Testing

Which Patients Qualify for Calreticulin


Susan Leclair, PhD, CLS (NCA)

Chancellor Professor, Department of Laboratory Science

University of Massachusetts, Dartmouth

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Tamara Lobban-Jones:

We got a question from Jean. Jean noticed a note on her lab report: Submit peripheral blood for calreticulin testing. She wants to know, what is this, and what kind of conversation should she be having with her hematologist?

Dr. Leclair:

We now know a whole lot more about myeloproliferative neoplasms than we did before. A little bit of history because—but not all the way back to the Egyptians, so not to worry—is that we didn't understand genetic processes until the 21st century. We're still getting to understand them. In 2006 we found the JAK2 and thought, well, this is it, this is the key to myeloproliferatives, except even up to maybe two years ago or so ET was a diagnosis of exclusion. That meant you didn't have myelofibrosis and you didn't have p. vera, but you had these funny values, so I guess that had to be essential

thrombocythemia. Calreticulin is a gene that controls the formation of reticulin and fibrosis, something that's—and platelets, something that's very commonly abnormal in essential thrombocythemia. So this note was saying, gee, golly, wiz, we don't actually know what's going on here, but there's a lot of platelets floating around or there's a lot of other issues here, and in my guess would be you should probably try this test. That's kind of the description of it. It's relatively new. The name kind of gives it away. Reticulin, you know it's talking about fibrosis.