What causes the destruction of red cells in hereditary ...

[Brittanyd9008]

What causes the destruction of red cells in hereditary spherocytosis?
 
  a. Complement activation
  b. Bound autoantibodies
  c. Phagocytosis by peripheral monocytes
  d. Phagocytosis by splenic macrophages

Question 2

Which of the following test results suggests significant hemoglobinemia may be present in a sample?
 
  a. Elevated mean cell volume (MCV)
  b. Reticulocytosis
  c. Hemoglobin less than 10 g/dL
  d. Unrealistically high mean cell hemoglobin concentration (MCHC)

[tkempin]

Answer to Question 1

ANS: D
The spherocytes found in hereditary spherocytosis are rigid and not as deformable as the normal biconcave red cell. The spleen selectively sequesters these abnormal red cells as they move through the spleen, where they become further damaged and are selectively removed by macrophages in the red pulp of the spleen.

Answer to Question 2

ANS: D
When red cells are lysed in the circulation with the resultant release of hemoglobin into plasma, the red cell count and thus hematocrit will be decreased. However, if enough hemoglobin exists in plasma, then it will be measured as hemoglobin in the hemoglobin test, thus increasing the hemoglobin concentration relative to the number of red cells (and thus hematocrit). This will lead to an elevated MCHC that can exceed the upper limit of the reference range.