Deck 23: Intrinsic Defects Leading to Increased Erythrocyte Destruction

Question 1

Which of the following is normal in hereditary spherocytosis?

A) Red cell morphology
B) Direct antiglobulin test
C) Osmotic fragility
D) Reticulocyte count

Answer 1

Direct antiglobulin test

Question 2

What red cell morphology, using Wright stain, is seen in patients with G6PD deficiency during a hemolytic episode?

A) Bite cells and polychromasia
B) Heinz bodies
C) Acanthocytes and crenated cells
D) Red cells are normal

Answer 2

Bite cells and polychromasia

Question 3

All of the following would be expected 1 year after a splenectomy on a patient with severe hereditary spherocytosis except:

A) Spherocytes on the blood film
B) Howell-Jolly bodies
C) Reticulocyte count of 10%
D) Siderocytes

Answer 3

Reticulocyte count of 10%

Question 4

What is the typical clinical course for those with G6PD A^-?

A) Severe anemia from infancy onward
B) Moderate anemia throughout adulthood
C) No anemia until exposure to an oxidant drug causes acute hemolysis
D) Benign because it does not cause anemia

Question 5

What is the most common red cell morphologic finding in PK deficiency?

A) Elliptocytes
B) Polychromasia and echinocytes (crenated)
C) Heinz bodies and spherocytes
D) Microcytes and hypochromasia

Question 6

Red cells acquiring a reduced surface area from losing unsupported membrane because of a deficiency of skeletal proteins describes hereditary:

A) Spherocytosis
B) Stomatocytosis
C) Pyropoikilocytosis
D) Acanthocytosis

Question 7

What treatment is most common for hereditary elliptocytosis patients who are anemic and show signs of hemolysis?

A) No treatment available
B) Drugs to prolong RBC life span
C) Splenectomy
D) Transfusions

Question 8

Which of the following is a typical finding in hereditary spherocytosis?

A) Increased mean cell hemoglobin concentration (MCHC)
B) Normal reticulocytes
C) Reduced fragility of red cells
D) Normal spectrin

Question 9

Cells with a slit (stomatocytes) instead of a round central pallor can be found in all of the following except:

A) Liver disease of alcoholism
B) Rh_null disease
C) Hereditary elliptocytosis
D) Blood films with a drying artifact

Question 10

What red cell morphology is associated with abetalipoproteinemia, liver disease, and McLeod blood group?

A) Acanthocytes
B) Stomatocytes
C) Spherocytes
D) Elliptocytes

Question 11

What ethnic group most often has glucose-6-phosphate dehydrogenase (G6PD) A^- in the United States?

A) Northern European male subjects
B) Asian American female subjects
C) African American female subjects
D) African American male subjects

Question 12

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 13

A patient with a small number of spherocytes, increased reticulocytes, and increased MCHC has a normal osmotic fragility. Select the best course of action.

A) Dismiss the spherocytes as an artifact.
B) Repeat the osmotic fragility after incubating the blood at 37 $\degree$ C for 24 hours.
C) Check the cell counter for errors in the MCHC.
D) Collect a new blood sample.

Question 14

What red cell morphology is often seen in patients with uremia?

A) Spherocytes
B) Echinocytes
C) Elliptocytes
D) Stomatocytes

Question 15

Which of the following can distinguish immune hemolytic anemia from hereditary spherocytosis in a patient with spherocytes?

A) Osmotic fragility
B) Reticulocyte count
C) Presence of polychromasia
D) Direct antiglobulin test

Question 16

A patient in the hospital for a hemolytic crisis after an infection has Heinz bodies when his blood is incubated with crystal violet. The fluorescent enzyme-screening test for G6PD is normal. Select the best course of action.

A) Repeat the red cell examination with new methylene blue stain.
B) Repeat the enzyme test several weeks after the hemolytic crisis.
C) Perform an osmotic fragility test.
D) Perform a haptoglobin test.

Question 17

The most common inherited anemia found in people of Northern European extraction is hereditary:

A) Elliptocytosis
B) Stomatocytosis
C) Spherocytosis
D) Pyropoikilocytosis

Question 18

A patient with a previously compensated hereditary spherocytosis has a severe drop in hemoglobin after a parvovirus infection. This represents what type of crisis?

A) Megaloblastic
B) Hemolytic
C) Aplastic
D) Anemic

Question 19

What is the most common enzyme deficiency of the glycolytic pathway?

A) Aldolase
B) Enolase
C) Lactic dehydrogenase (LDH)
D) Pyruvate kinase (PK)

Question 20

What is the best test to confirm the diagnosis of PK?

A) PK enzyme assay
B) Reticulocyte count
C) Haptoglobin test
D) Urine hemosiderin test

Question 21

Which of the following tests can confirm a paroxysmal nocturnal hemoglobinuria diagnosis in a patient?

A) Sucrose hemolysis test (sugar water test)
B) Reticulocyte count
C) Ham test (acidified serum lysis test)
D) Flow cytometry for cell surface markers

Question 22

Which of the following is a typical finding in paroxysmal nocturnal hemoglobinuria?

A) Hemosiderin in urine sediment
B) Normal levels of decay accelerating factor (CD55)
C) Hemolysis when blood is alkaline
D) Elevated white cells and platelets

Question 23

In most patients with hereditary spherocytosis, the condition is:

A) Inherited as an autosomal dominant trait
B) Inherited as an autosomal recessive trait
C) Inherited as an X-linked recessive trait
D) Acquired after viral infection

Question 24

Paroxysmal nocturnal hemoglobinuria is:

A) Inherited as an X-linked recessive trait
B) Acquired as a clonal disorder
C) Inherited as an autosomal dominant disorder
D) Acquired after a viral infection

Question 25

Hereditary spherocytosis is the result of a defect in:

A) Hemoglobin structure
B) Red cell membrane lipid bilayer
C) Red cell membrane skeletal proteins
D) Rate of synthesis of globin chains

Question 26

Which of the following is a true statement regarding G6PD?

A) The gene is located on chromosome 22.
B) The gene has the greatest degree of variability in the human genome.
C) The deficiency is primarily expressed as a clinical disease in heterozygous female subjects.
D) The normal enzyme is called G6PD A.

Question 27

Why is G6PD important for normal red cell survival?

A) Hemoglobin oxygen affinity is increased in its absence.
B) It is required to regenerate reduced glutathione.
C) It is required for insertion of iron into the protoporphyrin ring to form heme.
D) ( $\alpha$ ) Chains are produced in excess in its absence.

Question 28

What destroys the red cells in paroxysmal nocturnal hemoglobinuria?

A) Macrophages in the bone marrow
B) Antibodies against red cell membrane antigens
C) Increased susceptibility to complement
D) Macrophages in the spleen

Question 29

The inability to attach proteins requiring a glycosylphosphatidylinositol (GPI) link to the membrane surface is found in:

A) Paroxysmal nocturnal hemoglobinuria
B) Hereditary spherocytosis
C) Paroxysmal cold hemoglobinuria
D) Hereditary elliptocytosis