Which laboratory finding is typically elevated in polycythemia vera?

Which laboratory finding is typically elevated in polycythemia vera?

• A. White blood cell count
• B. Hemoglobin and hematocrit levels
• C. Platelet count
• D. Reticulocyte count

Answer: (B)

Polycythemia vera is a myeloproliferative disorder driven by a clonal expansion of erythroid cells, leading to a marked increase in red cell mass. Because there are more red cells in the blood, the hemoglobin concentration and the hematocrit rise—the clearest and most characteristic laboratory finding. Erythropoietin levels are typically suppressed due to feedback from the increased red cell mass, helping distinguish PV from secondary causes of erythrocytosis. While white blood cell and platelet counts can also be elevated in PV, they’re not the defining feature. Reticulocyte counts may be higher as part of overall marrow activity, but the standout, most specific lab change is the elevation of Hb and Hct reflecting erythrocytosis.

Polycythemia vera is a myeloproliferative disorder driven by a clonal expansion of erythroid cells, leading to a marked increase in red cell mass. Because there are more red cells in the blood, the hemoglobin concentration and the hematocrit rise—the clearest and most characteristic laboratory finding. Erythropoietin levels are typically suppressed due to feedback from the increased red cell mass, helping distinguish PV from secondary causes of erythrocytosis. While white blood cell and platelet counts can also be elevated in PV, they’re not the defining feature. Reticulocyte counts may be higher as part of overall marrow activity, but the standout, most specific lab change is the elevation of Hb and Hct reflecting erythrocytosis.