Secondary polycythemia (also called reactive polycythemia) is a disorder characterized by excessive production of circulating red blood cells (RBCs) due to hypoxia, tumor, or disease.
Secondary polycythemia may result from increased production of erythropoietin. This hormone, which is possibly produced and secreted in the kidneys, stimulates bone marrow production of RBCs. Increased production may be a compensatory physiologic response to hypoxemia, which may result from:
❑ chronic obstructive pulmonary disease
❑ hemoglobin (Hb) abnormalities (such as carboxyhemoglobinemia, which is seen in heavy smokers)
❑ heart failure (causing a decreased ventilation-perfusion ratio)
❑ right-to-left shunting of blood in the heart (as in transposition of the great vessels)
❑ central or peripheral alveolar hypoventilation (as in barbiturate intoxication or pickwickian syndrome)
❑ low oxygen content at high altitudes.
Increased production of erythropoietin may also be an inappropriate (pathologic) response to renal disease (such as renal vascular impairment, renal cysts, or hydronephrosis), to central nervous system disease (such as encephalitis and parkinsonism), to neoplasms (such as renal tumors, uterine myomas, or cerebellar hemangiomas), or to endocrine disorders (such as Cushing’s syndrome, Bartter’s syndrome, or pheochromocytomas). Rarely, secondary polycythemia results from a recessive genetic trait.
Secondary polycythemia occurs in approximately 2 out of every 100,000 people living at or near sea level; incidence rises among those living at high altitudes.
In the hypoxic patient, suggestive physical findings include ruddy cyanotic skin, emphysema, and hypoxemia without hepatosplenomegaly or hypertension. Clubbing of the fingers may occur if the underlying disease is cardiovascular. When secondary polycythemia isn’t caused by hypoxemia, it’s usually an incidental finding during treatment of an underlying disease.
Unlike polycythemia vera, secondary polycythemia isn’t associated with leukocytosis or thrombocytosis.
The goal of treatment is correction of the underlying disease or environmental condition. In severe secondary polycythemia in which altitude is a contributing factor, relocation may be advisable. If secondary polycythemia has produced hazardous hyperviscosity or if the patient doesn’t respond to treatment of the primary disease, reduction of blood volume by phlebotomy or pheresis may be effective. Emergency phlebotomy is indicated for prevention of impending vascular occlusion or before emergency surgery. In the latter case, it’s usually advisable to remove excess RBCs and reinfuse the patient’s plasma.
Because a patient with polycythemia has an increased risk of hemorrhage during and after surgery, elective surgery should be avoided until polycythemia is controlled. Generally, secondary polycythemia disappears when the primary disease is corrected.
❑ Keep the patient as active as possible to decrease the risk of thrombosis due to increased blood viscosity.
❑ Reduce calorie and sodium intake to counteract the tendency toward hypertension.
❑ Before and after phlebotomy, check blood pressure with the patient lying down. After the procedure, have the patient drink 24 oz (710 ml) of water or juice. To prevent syncope, have him sit upright for about 5 minutes before walking.
❑ Emphasize the importance of regular blood studies (every 2 to 3 months), even after the disease is controlled.
❑ Teach the patient and his family about the underlying disorder. Help them understand its relationship to polycythemia and the measures needed to control both.
❑ Teach the patient to recognize symptoms of recurring polycythemia and the importance of reporting them promptly.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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Title: Professional Guide to Diseases (Eighth Edition)
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2005
ISBN: 1-58255-370-X
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