What is secondary polycythemia?

Updated: Jul 20, 2020
  • Author: Srikanth Nagalla, MBBS, MS, FACP; Chief Editor: Sara J Grethlein, MD, FACP  more...
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Answer

In secondary polycythemia, the number of red blood cells (RBCs) is increased as a result of an underlying condition. Secondary polycythemia would more accurately be called secondary erythrocytosis or erythrocythemia, as those terms specifically denote increased red blood cells. The term polycythemia is used appropriately in the myeloproliferative disorder called polycythemia vera, in which there are elevated levels of all three peripheral blood cell lines—RBCs, white blood cells, and platelets. [1, 2]

Secondary polycythemia most often develops as a response to chronic hypoxemia, which triggers increased production of erythropoietin by the kidneys. The most common causes of secondary polycythemia include obstructive sleep apnea, obesity hypoventilation syndrome, and chronic obstructive pulmonary disease (COPD). [3] Other causes include testosterone replacement therapy [4] and heavy cigarette smoking. Patients who have arteriovenous or intracardiac shunting can present with polycythemia without hypoxemia. Erythropoietin-secreting tumors (eg, hepatocellular carcinoma, renal cell carcinoma, adrenal adenoma) cause some cases.


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