A high concentration of red cells in the venous blood, as indicated by hematocrit, red cell count, or hemoglobin concentration, is likely to be accepted as evidence of an increased amount of circulating red cells. An increased amount of circulating red cells may be a primary disorder (polycythemia vera), or it may be secondary to cardiopulmonary disease or low environmental oxygen tension.1
It is possible to have a high concentration of red cells in the venous blood without an increase in total red cell volume. A group of such patients, studied by Lawrence and Berlin,2 was found to have some of the symptoms of polycythemia vera: ruddy complexion, headache, easy fatigability, dizziness, etc. The total circulating red cell volumes were measured with radioactive phosphorus-labeled red cells and were found to be within normal limits, even though the venous hematocrits were greater than 50%. Since these findings are incompatible
BLUM AS, ZBAR MJ. Relative Polycythemia: Alterations of Red Cell Distribution Simulating Hemoconcentration. AMA Arch Intern Med. 1959;104(3):385–389. doi:10.1001/archinte.1959.00270090039006
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