Anemia is a common condition encountered in inpatient and outpatient primary care settings. When anemia is detected, it is essential to investigate the cause to provide appropriate treatment. Patients may present with symptomatic anemia (eg, fatigue, weakness, shortness of breath), or anemia may be an incidental finding on laboratory evaluation. Initial evaluation consists of a thorough history and physical examination and a complete blood cell count (CBC). Careful examination of the CBC and the mean corpuscular volume provides important clues to the classification and cause of anemia. Supplemental tests may include a peripheral blood smear; reticulocyte count; iron panel (ie, ferritin and iron levels, total iron-binding capacity, transferrin saturation); and levels of vitamin B₁₂, folate, lactate dehydrogenase, haptoglobin, and bilirubin.

Case 1. DB is a 45-year-old patient with hypertension, prediabetes, and hyperlipidemia who comes to your office because of 6 months of increasing fatigue. In the past month, she has been short of breath when she climbs stairs. She reports very dark stools for several months but no frank rectal bleeding or bleeding from any other source. She had a hysterectomy 2 years ago for symptomatic fibroids. On physical examination, you note pallor of skin and conjunctivae. The results of a complete blood cell count (CBC) show the hemoglobin level is low at 9.7 g/dL. One year ago, it was normal at 12.5 g/dL.

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