Anemia in Pregnancy with Normal Iron Studies
Apr 2010 – by M. Mennuti, MD
The most common cause of a microcytic anemia in a pregnant patient who is not iron deficient is the presence of a thalassemia mutation in one of her hemoglobin genes. Thalassemia carriers can be identified by evaluating patients who have an MCV <80fL. Although thalassemia genes occur world-wide, beta thalassemia is more common among people of Mediterranean origin and alpha thalassemia is most common in Asians. Patients who carry a beta thalassemia mutation will usually demonstrate a mild elevation of hemoglobin A2 by hemoglobin electrophoresis. Alpha thalassemia is most commonly due to deletion rather than mutation of a gene that codes for the alpha chain of hemoglobin. Hemoglobin electrophoresis performed on alpha thalassemia carriers is usually normal. Diagnosis of an alpha thalassemia trait requires molecular evaluation to detect deletions, or less commonly mutations, of the gene for the alpha chain of hemoglobin.
Carriers of either alpha or beta thalassemia trait generally have a life-long mild microcytic anemia. They should not be treated empirically with iron as they often have increased iron stores due to increased absorption. They have increased red cell turnover that leads to a greater need for folic acid and folic acid supplementation is recommended. Couples in whom both partners are carriers of a beta thalassemia gene or both carriers an alpha thalassemia gene are at 25% risk of having an affected child. Prenatal diagnosis is available by CVS or amniocentesis. Donor gametes or preimplantation genetic diagnosis are options that can also be used to reduce the reproductive risk.