hematology and oncology
Secondary Erythrocytosis
Etiology of Secondary Erythrocytosis
Common causesof secondary erythrocytosis include Smoking Chronic arterial hypoxemia Tumors (tumor-associated erythrocytosis) Use of androgenic steroids Surreptitiouserythropoietinuse Less commoncauses include certain congenital disorders such as High oxygen-affinity hemoglobinopathies Erythropoietinreceptor mutations Chuvash polycythemia (in which a mutation in theVHLgene affects the hypoxia-sensing pathway and increases inerythropoietinproduction.) Right to left arteriovenous shunts in the lungs Proline hydroxylase 2 and hypoxia-inducible factor 2 alpha (HIF-2α) mutations Spurious erythrocytosis may occur with hemoconcentration (eg, due to burns, diarrhea, or diuretic use). In patients who smoke cigarettes, reversible erythrocytosis results mainly from tissue hypoxia due to elevation of blood carboxyhemoglobin concentration, and there is usually plasma volume reduction. Levels will normalize with smoking cessation. 92%), typically due to lung disease, right-to-left intracardiac shunts, renal transplantation, prolonged Altitude Illness , or hypoventilation syndromes, often develop erythrocytosis. The primary treatment is to alleviate the underlying condition, but oxygen therapy may help, and Tumor-associated erythrocytosis can occur when renal tumors, cysts, hepatomas, cerebellar hemangioblastomas, or uterine leiomyomas secreteerythropoietin. Removal of the lesion is curative. High oxygen–affinity hemoglobinopathies are very rare. This diagnosis is suggested by a family history of erythrocytosis; it is established by measuring the P50 (the partial pressure of oxygen at which hemoglobin becomes 50% saturated) and, if possible, determining the complete oxyhemoglobin dissociation curve (see figure). Standard hemoglobin electrophoresis may be normal and cannot reliably exclude this cause of erythrocytosis. 