July 25, 2016
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Polycythemia (High Red Blood Cell Count) (cont.)

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What are the common causes of secondary polycythemia?

Secondary polycythemia is usually due to increased erythropoietin (EPO) production either in response to chronic hypoxia (low blood oxygen level) or from an erythropoietin secreting tumor.

Chronic hypoxia

Common conditions causing chronic hypoxia are chronic lung diseases such as:

Abnormal blood flow to the kidneys can be perceived by the kidneys as decreased oxygenation (renal hypoxia), even though, other tissues may have normal oxygenation. Renal hypoxia may promote an increase in erythropoietin production. This condition can occur after kidney transplantation or narrowing of renal arteries (blood vessels supplying the kidneys).

People living in high altitudes can develop polycythemia. In high altitudes, increased red blood cell production occurs in order to compensate for the low ambient oxygen levels and inadequate tissue oxygenation.

Rare congenital defects in the hemoglobin molecule, such as 2, 3-BPG deficiency, can result in a higher oxygen affinity by hemoglobin. In these conditions, oxygen is held on tightly by hemoglobin and is less readily released from hemoglobin to the tissues. The resulting tissue hypoxia from poor oxygen delivery may lead to polycythemia.

Erythropoietin secreting tumors

Certain tumors can release increased amount of erythropoietin. The most common erythropoietin secreting tumors are:

Occasionally, benign kidney cysts and kidney obstruction (hydronephrosis) can also secrete extra erythropoietin causing polycythemia.

A rare genetic condition, called Chuvash polycythemia, causes increased activity of the gene that produces erythropoietin. The overproduction of erythropoietin causes polycythemia.

Medically Reviewed by a Doctor on 2/23/2016

Source: MedicineNet.com

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