Q. A 62-year-old woman comes to your clinic with complaints of fatigue and dyspnea upon exertion. Two years ago, she was diagnosed with rheumatoid arthritis and started therapy with methotrexate. On clinical examination, you appreciate pallor of the skin, conjunctiva, and mucus membranes. You order a series of iron studies, which are shown below. What is the pathophysiology of this patient's condition?