Quantitative Changes in Blood Cells

This chapter deals with quantitative changes in blood cells, first the causes of increased cell counts for each lineage, then the causes of decreased counts. An increase of a cell type usually results either from redistribution of cells or from increased bone marrow output; occasionally an increased count, most noticeably of red cells, can result from a decrease of plasma volume. A decreased count of any cell type can result from diminished bone marrow output, redistribution or shortened survival in the circulation. The absolute number of lymphocytes, monocytes, eosinophils and basophils also increases, but because of the more striking increase in neutrophil numbers the increase of other cell types may go unnoticed. In lymphoproliferative disorders, lymphocytosis is usually caused by the presence of considerable numbers of lymphoma cells in the peripheral blood.