Hemolytic anemia

Hemolytic anemia is defined as the destruction of red blood cells (RBCs) before their normal 120-day life span. While hemolysis can be a lifelong asymptomatic condition, it most often presents as anemia when erythrocytosis cannot match the pace of red cell destruction.

Premature destruction of RBCs can occur intravascularly or extravascularly in the reticuloendothelial system, although the latter is more common. Intravascular hemolysis is the destruction of red blood cells in the circulation with the release of cell contents into the plasma. The intravascular mechanisms include direct cellular destruction, fragmentation, and oxidation. Direct cellular destruction is caused by toxins, trauma, or lysis.

The more common extravascular hemolysis is the removal and destruction of red blood cells with membrane alterations by the macrophages of the spleen and liver.

Classification of Hemolytic anemias
1. Red cell abnormality

* Hereditary
* Acquired

2. Extracorpuscular factors

*Immune hemolytic anemias
*Nonimmune hemolytic anemias

Hemolytic anemias can also be classified according to whether the cause of hemolysis is intrinsic or extrinsic to the RBC— damage from within or without.
*Intrinsic causes of hemolysis include abnormalities of hemoglobin, the RBC membrane, or RBC enzymes.
*Extrinsic causes include RBC-directed antibodies, a disordered vasculature, infections, or toxins.

Hemolysis should be considered when a patient experiences acute jaundice or hematuria in the presence of anemia. Symptoms of chronic hemolysis include lymphadenopathy, hepatosplenomegaly, cholestasis, and choledocholithiasis. Other nonspecific symptoms include fatigue, dyspnea, hypotension, and tachycardia.
Hemolytic anemia