Review Question - QID 214951

A 45-year-old woman presents to the primary care clinic for joint aches and fatigue. For the past 2 years, she has experienced increasing achiness at the base of her fingers in both hands. The pain is now so severe that it impairs her ability to work. She reports that the joints feel stiff in the morning but improve through the day. The patient was also diagnosed with trigeminal neuralgia 2 weeks ago and was started on carbamazepine. Other medical history includes alcoholic hepatitis. She has 5-6 glasses of wine each night and has done so for the past 5 years. She never eats breakfast and regularly skips dinner to drink alcohol. Her temperature is 97.6°F (36.4°C), blood pressure is 108/74 mmHg, pulse is 68/min, and respirations are 16/min. Physical exam reveals a thin-appearing woman with tenderness and moderate swelling over her metacarpophalangeal (MCP) joints bilaterally. Her laboratory results are as follows:

Hemoglobin: 9.4 g/dL
Hematocrit: 29.1%
Leukocyte count: 7,500/mm^3
Platelet count: 200,000/mm^3
Mean corpuscular volume (MCV): 90 µm^3
Reticulocyte count: 0.5%
Transferrin: 120 mg/dL (reference range: 170-370 mg/dL)
Ferritin: 250 ng/mL (reference range: 12-150 ng/mL)
Lactate dehydrogenase: 150 U/L

What is the underlying cause of her anemia?