Ten years later, the patient described in Questions 3 and 4 experiences recurrent hemarthroses that become refractory to standard doses of factor VIII. The most likely cause of this is

Correct Answer: B

Rationale: Factor VIII inhibitors (B) are a common complication in hemophilia A, causing resistance to replacement therapy and recurrent bleeds.

Correct Answer: B

Rationale: Aplastic anemia (B) is normocytic due to marrow failure without RBC size alteration.

Correct Answer: B

Rationale: Hypothyroidism (B) typically causes normocytic anemia due to reduced erythropoiesis.

Correct Answer: A

Rationale: Diamond-Blackfan anemia (A) features elevated HbF as a compensatory mechanism.

Correct Answer: A

Rationale: GI blood loss (A) is a common cause of persistent iron deficiency; thalassemia (B) and milk allergy (E) are also possible, but A is most likely given the context.