A 27-year-old woman presents to her physician with complaints of fatigue lasting over a year. She first noticed the fatigue following the birth of her second child, although both pregnancies were uncomplicated. She was informed during each pregnancy that she had anemia. Past medical history is otherwise unremarkable, and she does not take any medications. Vital signs are within normal limits. On physical examination, no abnormalities are noted. Laboratory findings are as follows:
A) Beta-thalassemia trait
Anemia can be classified based on the mean corpuscular volume (MCV) into microcytic, normocytic, or macrocytic categories. Microcytic anemia (MCV < 80 µm3) has common causes that include iron deficiency, anemia of chronic disease, thalassemia, and sideroblastic anemia. This patient’s low MCV and mild anemia suggest a microcytic process, with the elevated fraction of hemoglobin A2 being characteristic of beta-thalassemia trait.
Answer choice B: Iron deficiency anemia, is incorrect. While iron deficiency anemia can cause microcytosis, it is not typically associated with increased levels of hemoglobin A₂. Iron deficiency anemia is associated with decreased ferritin and decreased transferrin saturation.
Answer choice C: Lead poisoning, is incorrect. Lead poisoning can lead to microcytic anemia, but it does not cause elevated hemoglobin A2 levels.
Answer choice D: Sickle cell disease, is incorrect. Sickle cell disease usually presents with normocytic or mildly macrocytic anemia and would not be associated with elevated hemoglobin A2.
Answer choice E: Sideroblastic anemia, is incorrect. Sideroblastic anemia can present as a microcytic anemia but is not associated with increased hemoglobin A₂ levels and often shows ringed sideroblasts on bone marrow examination.
Key Learning Point
Beta-thalassemia trait is characterized by a microcytic anemia with a mild increase in hemoglobin A2 on hemoglobin electrophoresis, which distinguishes it from other causes of microcytic anemia such as iron deficiency and chronic disease.
