Question

Compare and contrast the intravascular and extravascular routes of hemoglobin degradation (identify at least two similarities and at least 3 differences)

Answer 1

Hemolysis is the premature destruction of RBCs due to intrinsic inherited defects in the RBCs or because of acquired intravascular abnormalities.

Difference between intravascular hemolysis and Extravascular hemolysis:

Hemolysis may be either intravascular or extravascular.
1. In intravascular hemolysis RBCs lyse in the circulation releasing hemoglobin into the plasma whereas In extravascular hemolysis RBCs are phagocytized by macrophages in the spleen and liver.

2. Intravascular hemolysis causes include mechanical trauma, complement fixation, and other toxic damage to the RBC whereas extravascular hemolysis causes include RBC membrane abnormalities such as bound immunoglobulin, or physical abnormalities restricting RBC deformability that prevent egress from the spleen.

3. In intravascular hemolysis, the fragmented RBCs are called schistocytes whereas Extravascular hemolysis is characterized by spherocytes.

Similarities:

01. Lactic dehydrogenase (LDH) level increase in both intravascular and Extravascular hemolysis.

02. Haptoglobin level decrease in both hemolysis.