Review Question - QID 214909

A 19-year-old African American man presents with 2 days of fatigue. One week ago, he developed general malaise and subjective fevers. He is visiting from Libya, where he has worked in a uranium mine for several years. He has required blood transfusions intermittently since childhood due to chronic anemia. His temperature is 100.5°F (38.1°C), blood pressure is 112/62 mmHg, pulse is 120/min, and respirations are 22/min. Physical exam is notable for scleral icterus and hyperdynamic pulses. Laboratory workup shows:

Leukocyte count: 11,000 /mm^3
Hemoglobin: 4.2 g/dL
Platelet count: 240,000 /mm^3
Mean corpuscular volume: 82 µm^3
Mean corpuscular hemoglobin concentration: 34%
Reticulocyte count: 1%
Lactate dehydrogenase: 330 U/L
Haptoglobin: 14 mg/dL
Direct Coombs: No agglutination of red blood cells

Serum:
Total bilirubin: 3.3 mg/dL
Direct bilirubin: 0.2 mg/dL

Which of the following is the most likely underlying cause of this patient’s anemia?