Pathophysiology Q&A | Pathophysiology
1. A 22-year-old woman presents with fatigue, pallor, and heavy menstrual
bleeding. Laboratory studies show hemoglobin 8.5 g/dL, MCV 72 fL, serum
ferritin 5 ng/mL, and normal vitamin B12 and folate levels. What is the most
likely diagnosis?
A) Vitamin B12 deficiency anemia
B) Folic acid deficiency anemia
C) Iron deficiency anemia
D) Anemia of chronic disease
Correct Answer: Iron deficiency anemia
Rationale: Iron deficiency anemia is characterized by microcytic (low MCV)
and hypochromic red blood cells, low serum ferritin (indicating depleted iron
stores), and occurs in the setting of chronic blood loss (heavy menses). The
normal B12 and folate levels rule out macrocytic anemias.
2. A patient with chronic renal failure is found to have a normocytic,
normochromic anemia. This type of anemia is primarily caused by:
A) Iron deficiency
B) Vitamin B12 deficiency
C) Decreased erythropoietin production
D) Hemolysis
Correct Answer: Decreased erythropoietin production
Rationale: The kidneys produce erythropoietin (EPO), which stimulates red
blood cell production in the bone marrow. In chronic renal failure, damaged
kidneys produce insufficient EPO, leading to a normocytic, normochromic
anemia.
3. Which of the following is a key pathophysiologic feature of sickle cell
anemia?
A) Increased red blood cell production
,B) A point mutation in the beta-globin gene
C) Iron overload
D) Decreased platelet count
Correct Answer: A point mutation in the beta-globin gene
Rationale: Sickle cell anemia is caused by a single nucleotide substitution
(point mutation) in the beta-globin gene, resulting in the production of
abnormal hemoglobin S. Under low oxygen conditions, hemoglobin S
polymerizes, causing red blood cells to sickle.
4. A patient with sickle cell disease presents with acute chest pain, fever,
and hypoxia. This is most consistent with:
A) Aplastic crisis
B) Splenic sequestration
C) Acute chest syndrome
D) Vaso-occlusive crisis
Correct Answer: Acute chest syndrome
Rationale: Acute chest syndrome is a leading cause of death in sickle cell
disease, characterized by chest pain, fever, pulmonary infiltrates, and
hypoxia. It is often triggered by infection or fat embolism from bone marrow
infarction.
5. A patient with immune thrombocytopenic purpura (ITP) has a platelet
count of 15,000/µL. The underlying pathophysiologic mechanism is:
A) Decreased bone marrow production of platelets
B) Increased platelet destruction by autoantibodies
C) Sequestration of platelets in the spleen
D) Disseminated intravascular coagulation
Correct Answer: Increased platelet destruction by autoantibodies
,Rationale: ITP is an autoimmune disorder in which autoantibodies (usually
IgG) bind to platelet membrane glycoproteins, marking them for destruction
by macrophages in the spleen, leading to severe thrombocytopenia.
6. A patient with heparin-induced thrombocytopenia (HIT) develops a low
platelet count and a deep vein thrombosis. The pathophysiologic mechanism
of HIT involves:
A) Direct bone marrow suppression
B) Autoantibodies against platelet factor 4 (PF4) complexed with heparin
C) Splenic sequestration of platelets
D) Decreased platelet production
Correct Answer: Autoantibodies against platelet factor 4 (PF4) complexed
with heparin
Rationale: HIT is an immune-mediated disorder in which antibodies recognize
PF4 bound to heparin, forming immune complexes that activate platelets,
leading to both thrombocytopenia and paradoxical thrombosis.
7. A patient with chronic myeloid leukemia (CML) has the Philadelphia
chromosome. This chromosomal abnormality results in the formation of
which fusion gene?
A) PML-RARA
B) BCR-ABL
C) EWS-FLI1
D) PAX3-FOXO1
Correct Answer: BCR-ABL
Rationale: The Philadelphia chromosome is a translocation between
chromosomes 9 and 22, resulting in the BCR-ABL fusion gene. This gene
produces a constitutively active tyrosine kinase that drives uncontrolled
proliferation of leukemic cells.
, 8. A patient with Hodgkin lymphoma presents with a painless, enlarged
cervical lymph node. A biopsy reveals which pathognomonic cell type?
A) Leukemic blast
B) Reed-Sternberg cell
C) Plasma cell
D) Burkitt cell
Correct Answer: Reed-Sternberg cell
Rationale: Reed-Sternberg cells are large, multinucleated cells that are the
hallmark of Hodgkin lymphoma. Their presence in a lymph node biopsy is
diagnostic and distinguishes it from non-Hodgkin lymphomas.
9. A patient with hemophilia A has a deficiency of which clotting factor?
A) Factor II
B) Factor VIII
C) Factor IX
D) Factor XI
Correct Answer: Factor VIII
Rationale: Hemophilia A is an X-linked recessive disorder caused by a
deficiency of clotting factor VIII. Hemophilia B is caused by a deficiency of
factor IX.
10. Von Willebrand disease is characterized by a deficiency of von Willebrand
factor (vWF). What is the primary function of vWF?
A) To activate factor X
B) To stabilize factor VIII and promote platelet adhesion
C) To convert fibrinogen to fibrin
D) To activate plasminogen
Correct Answer: To stabilize factor VIII and promote platelet adhesion