A 40-year-old woman visits the clinic complaining of fatigue. She had recently been treated for an infection. Her laboratory values are RBC 1.8 X 100/μl, Hb 5.2 g/dL, hematocrit (Hct) 15, WBC 7.6 X 10/μl, platelet count 320,000/µl, mean corpuscular volume (MCV) 92 fL, and reticulocyte count 24% . What is the most likely explana tion for this presentation?