Basics of Hemolysis and Intravascular Hemolysis MCQs

In intravascular hemolysis, destruction of RBC leads to hemoglobinemia. Excess of haemoglobin may be excreted by kidney called hemoglobinuria. Some of the haemoglobin is reabsorbed in kidney and is converted to hemosiderin which is then excreted as hemosiderinuria. Free haemoglobin in plasma bound to haptoglobin, and this complex is rapidly cleared by mononuclear phagocytic system - Decreased haptoglobin When haptoglobin is depleted, free haemoglobin is oxidized to methemoglobin - methemoglobinemia Excess heme groups are catabolized to bilirubin within the mononuclear phagocytic system - Increased indirect bilirubin and jaundice LDH is stored in blood. During hemolysis this enzyme is released in the blood - Increased serum LDH. Reference: Robbins, 8 th edition, page number - 642

Acquired mutation of phosphatidyl inositol Glycan complement group A gene (PIGA) Deficient in CD55, CD59, C8 binding protein CD59 prevents activation of alternate pathway Chronic hemolysis without hemoglobinuria is typical Intravascular hemolysis Loss of heme iron can cause IDA Thrombosis is the leading cause of disease related death in individuals with PNH. 5% develop AML. Diagnosis: Flow cytometry Treatment: Immunosuppressant and bone marrow transplant Hemolytic Anemia Hemolysis could be: Intracorpuscular Hereditary Defects Defects in RBC membrane Enzyme defects Hemoglobinopathies Thalassemia Syndromes Acquired Defects PNH Extracorpuscular (areas of sluggish circulation or hypo-oxygenation) Immunohemolytic anemia, infections, microangiopathic Reference: Robbins & cotran pathologic basis of diseases, 10 th edition Chapter 14, pg 648

Factor H inhibits alternative complement pathway by promoting destruction of C3b and C3 convertases. Polymorphisms in Factor H gene have been linked to Age related Macular Degeneration, an important cause of vision loss in elder population. Reference: Robbins & Cotran Pathologic Basis of Diseases 10 th edition, chapter 3, pg 87

PNH is diagnosed by flow cytometry, which provides a sensitive means for detecting red cells that are deficient in GPI-linked proteins such as CD59 and CD55. Reference: Robbins 9th/pg 643