This patient is a young woman with a history of mild anemia which has become worse since becoming pregnant. Her current CBC shows a moderate anemia and microcytosis with an increased RDW. The differential diagnosis for microcytic anemia is lengthy, including abnormal iron metabolism (iron deficiency, anemia of chronic disease, sideroblastic anemia, lead poisoning, defects of heme or porphoryin synthesis), thalassemia, and some hemoglobinopathies (hemoglobin C or E, but not S).

Her reticulocyte count is markedly elevated, but her corrected reticulocyte count is closer to normal (3.1%). Her RPI is less than 2, suggesting difficulty producing new blood cells. The patient’s ESR is slightly elevated and she has a normal ferritin, B12, folate and free T4.

Examining her peripheral smear, we see some microcytosis (compared to the adjacent lymphocyte), occasional target cells and conspicuous reticulocytes.

Hemoglobin electrophoresis and HPLC demonstrate a decreased amount of hemoglobin A and a mild to moderated increase in the amount of hemoglobin A2 and F.

Together these finding are most consistent with beta-thalassemia minor. However, it should be noted that her elevated RDW and the severity of her anemia is not typical for beta-thalassemia minor. Both can probably be attributed to her pregnancy. Effects which can be seen in pregnancy include a slight increase in MCV, percent hemoglobin F, reticulocyte percentage, and/or RDW as well as a slight decrease (dilutional) in RBC, hemoglobin and/or hematocrit.