Inherited Disorders of Hemoglobin Structure and Synthesis

Polycythemia is characterized by an increase in the number, and in the hemoglobin content, of circulating red cells. In patients who have chronic anoxia from impaired pulmonary ventilation or congenital or acquired heart disease, the increase in plasma erythropoietin leads to secondary polycythemia. Some renal cell carcinomas, hepatocarcinomas, and other tumors, which produce physiologically inappropriate amounts of erythropoietin, may also cause secondary polycythemia. Conversely, anemia can result from renal insufficiency and from chronic disorders that depress erythropoietin production. In polycythemia vera (primary polycythemia), which is a malignancy of erythrocyte stem cells of unknown cause, erythropoietin levels are normal or depressed. 

Although hemoglobin disorders are extremely diverse, they can be generally classified into two somewhat overlapping groups. 

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SECTION 28.3 Inherited Disorders of Hemoglobin Structure and Synthesis... 

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