Chapter 20 Hemolytic Anemias caused by physical injury to RBCs

Thrombotic Microangiopathic Anemia (TMA)/(MAHA)

microcirculatory lesions. presence of schistocytes, thrombocytopenia, ischemic damage to organs. damage of lining of small vessels. deposition of platelets and fibrin in microvasculature. thrombus formation in blood vessels. RBCs forced through fibrin strands in thrombus. Fragmented by the force of flowing blood

TMA disorders

classic shiga toxin producing E. coli hemolytic uremic syndrome. Atypical hemolytic uremic syndrome (aHUS). Thrombotic thrombocytopenic purpura (TTP). disseminated cancer, malignant hypertension, autoimmune disorders, sepsis. pregancy: preeclampsia, eclampsia, HELLP (hemolysis, elevated liver enzymes and low platelet count.

Malignant hypertension

caused by endothelial injury, fibrinoid necrosis of arterioles, deposition of fibrin. low platelets, rbc fragmentation, renal failure

Traumatic cardiac HA

Prosthetic heart valves. Massive hemolysis is rarely a complication. schistocytes from shear stress.

Thermal Injury

extensive thermal burns. heat causes denaturation of spectrin in RBC membranes. peripheral smear- rbc budding, schistocytes, spherocytes. Hemoglobinuria, hemoglobinemia decreased after 48 hours

Exercise induced hemoglobinuria

march (runners) hemoglobinuria. transient intravascular hemolysis. no anemai. Pressure in the soles during running and walking. no schistocytes. Hemoglobinuria and hemoglobinemia. iron deficiency can occur if exercise and hemolysis are frequent

HA caused by infectious agents

Malarial parasites (plasmodium falciparum), babesia microti, bartonella bacilliformis, clostridium perfringens

Animal venoms

bees, wasps, spiders, scorpions- brown recluse spider. localized lesions. damages rbc membrane, complement mediated lysis