Anemia that are associated with decreased RBC life span.
Hemolytic anemias are characterized by an increased rate of RBC destruction, a compensatory increase in erythropoiesis reticulocytosis and retention of iron ,marked erythroid hyperplasia within the marrow and an increased reticulocyte count in peripheral blood
in severe hemolytic anemias, extramedullary hematopoiesis may develop in the spleen, liver, and lymph nodes.
The causes are - Intracorpuscular and Extracorpuscular hemolytic anemia.
According to mechanism of RBC destruction hemolytic anemia can be intravacular or extravacular.
Because extreme alterations of shape are necessary for RBCs to successfully navigate the splenic sinusoids, reduced flexibility makes this passage difficult and leads to splenic sequestration, followed by phagocytosis.
Schematic of splenic sinus (electron micrograph). A red cell is in the process of squeezing from the red pulp cords into the sinus lumen. Note the degree of deformability required for red cells to pass through the wall of the sinus.