Iron-Deficiency Anemia

IRON-DEFICIENCY ANEMIA 24A

A 65-year-old previously well man presents to the clinic with the complaint of fatigue of 3 months’ duration. Questioning reveals diffuse weakness and feeling winded when walking uphill or climbing more than one flight of stairs. All of his symptoms have slowly worsened over time. Except for light-headedness, the review of systems is negative. The patient has no significant medical history, social history, or family history. On physical examination, he appears somewhat pale, with normal vital signs except for a resting pulse of 118 beats/min. The physical examination is otherwise unremarkable except for his rectal examination, which reveals brown, guaiac-positive stool (consistent with occult blood in the stool). A complete blood count (CBC) reveals a microcytic anemia with low mean corpuscular volume (MCV).

What are the salient features of this patient’s problem? How do you think through his problem?

Salient features: Fatigue, weakness, and dyspnea of insidious onset; pale on physical examination; guaiac-positive stool; microcytic anemia

How to think through: Several of this patient’s symptoms and signs—fatigue, dyspnea, lightheadedness, weakness, and tachycardia—might suggest cardiac and pulmonary causes for your differential diagnosis. But do not forget anemia! After you establish that a patient is anemic, look at the reticulocyte count. Hyperproliferative anemia indicates either hemolysis or active bleeding. Hypoproliferative anemia, which is more common, often indicates a deficiency state. Anemia is further assessed by looking at the MCV. In iron-deficiency anemia, is the MCV low or high? (Low.) What do the serum iron studies—ferritin, iron, transferrin (total iron-binding capacity), and % saturation—show? What does the peripheral smear show? What is the platelet count in iron deficiency? Whenever you determine that the etiology of anemia is iron deficiency, you must investigate its cause. Conceptualize its possible causes by tracing the path from dietary iron intake to absorption to bioavailability to possible (blood) loss. What are the potential pathologies at each stage? For example, where is iron absorbed, and what might disrupt this absorption? Although the gastrointestinal (GI) tract is the most common source of blood loss, be sure to also consider other sources of blood loss (e.g., uterine, urinary, pulmonary).