What is the primary cause of secondary polycythemia?

Secondary polycythemia is predominantly caused by increased levels of erythropoietin, which often occur as a compensatory response to chronic hypoxia or due to the presence of certain tumors. In situations where there is inadequate oxygenation of tissues, such as chronic obstructive pulmonary disease (COPD), high altitude living, or certain heart conditions, the body responds by stimulating the kidneys to produce more erythropoietin. This hormone promotes the production of red blood cells in the bone marrow, ultimately leading to an increase in red blood cell mass and therefore, polycythemia.

Additionally, certain tumors, like renal cell carcinoma, can also secrete erythropoietin ectopically, resulting in high levels of this hormone independently of hypoxic conditions. The presence of increased erythropoietin is a hallmark of secondary polycythemia, thus directly linking it to the underlying causes associated with hypoxia or proliferative neoplasms.

Other causes listed, such as genetic mutations, decreased erythropoietin production, and bone marrow disorders, do not adequately explain the mechanism behind secondary polycythemia, as they lead to different forms of polycythemia or other hematological conditions. Understanding this distinction is crucial for