Review Question - QID 109880

This patient with normocytic anemia, a high reticulocyte count, decreased haptoglobin level, and schistocytes on peripheral blood smear most likely has an angiopathic anemia, which can be caused by an aortic valve replacement.

Angiopathic anemias are caused by shearing of red blood cells as they pass through blood vessels. These disorders can either occur due to microscopic etiologies such as ADAMTS13 activity or macroscopic mechanisms such as mechanical valves. Since angiopathic anemias cause an intravascular hemolysis, the hemoglobin in the lysed cells will bind with and decrease serum haptoglobin levels. Furthermore, the sheared cells will be present in the peripheral blood as fragments known as schistocytes. Finally, in these types of anemia there is no defect in red blood cell production so the percentage of reticulocytes will be high.

Figure A shows the helmet shaped red blood cell fragments known as schistocytes that are commonly seen in angiopathic anemia.

Incorrect Answers:
Answer 2: Consumption of fava beans could trigger anemia in patients with glucose-6-phosphate dehydrogenase deficiency; however, this disorder would present with Heinz bodies within red blood cells.

Answer 3: Infection of red blood cells can lead to hemolysis; however, these disorders would present with the infectious organism within the red blood cells.

Answer 4: Inheritance of a cytoskeletal defect can cause hereditary spherocytosis; however, this disorder would present with round red blood cells known as spherocytes on peripheral blood smear.

Answer 5: Red urine in the morning could result from paroxysmal nocturnal hemoglobinuria; however, this disorder would not present with schistocytes in the peripheral blood smear.

Bullet Summary:
Macroangiopathic anemia can be caused by physical factors such as heart valve replacement or calcified aortic valves.