A 28-year-old woman comes to the clinic complaining of worsening fatigue, exercise intolerance, and dizziness over the past three months. She reports heavy menstrual periods that have increased in duration and flow over the last year. Her past medical history is otherwise unremarkable, and she does not take any medications. Vital signs show she is tachycardic at 102/min. Her blood pressure is 114/72 mmHg. On physical examination, the patient appears pale, and conjunctival pallor is noted. Laboratory studies reveal a hemoglobin of 8.8 g/dL, mean corpuscular volume (MCV) of 74 fL, and a platelet count of 450,000/μL. A peripheral blood smear is ordered.
Which of the following findings is most likely to be seen on the peripheral blood smear?
The correct answer is:
C) Hypochromic, microcytic erythrocytes
This patient presents with signs and symptoms of iron deficiency anemia (IDA), evidenced by microcytic anemia (low hemoglobin and MCV) in the setting of chronic blood loss from menorrhagia. Iron is a critical component of heme, so when iron stores are depleted, hemoglobin synthesis is impaired. This results in the production of smaller red blood cells (microcytosis) that are paler than normal (hypochromic) because they contain less hemoglobin. Thrombocytosis (elevated platelets) is also a frequent, non-specific finding in severe iron deficiency.
Answer choice A: Basophilic stippling, is incorrect. Basophilic stippling represents aggregated ribosomal RNA and is classically associated with lead poisoning or thalassemia, not iron deficiency.
Answer choice B: Hypersegmented neutrophils, is incorrect. Hypersegmented neutrophils are the hallmark of megaloblastic anemia, caused by vitamin B12 or folate deficiency, which leads to DNA synthesis impairment rather than hemoglobin synthesis impairment.
Answer choice D: Ringed sideroblasts, is incorrect. Ringed sideroblasts are found in the bone marrow of patients with sideroblastic anemia, where iron accumulates in the mitochondria of erythroblasts because it cannot be incorporated into heme.
Answer choice E: Schistocytes, is incorrect. Schistocytes are fragmented red blood cells seen in microangiopathic hemolytic anemias (e.g., disseminated intravascular coagulation, thrombotic thrombycytopenic purpura, hemolytic uremic syndrome) caused by physical shear stress on the red blood cells within the vasculature.
Key Learning Point
Iron deficiency anemia is the most common cause of microcytic anemia. It is characterized by hypochromic, microcytic red blood cells on peripheral smear. In women of childbearing age, the most common etiology is chronic blood loss from menorrhagia. Lab work typically shows low ferritin, low serum iron, and high total iron-binding capacity (TIBC).
