From the Guidelines
Yes, you can have iron deficiency anemia with a normal MCV (normocytic). While iron deficiency anemia typically presents with microcytic (small) red blood cells, early or mild iron deficiency may initially show a normal MCV before progressing to microcytosis, as noted in the British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults 1. Additionally, if iron deficiency coexists with other conditions that cause macrocytosis (large cells), such as vitamin B12 or folate deficiency, the opposing effects can result in an apparently normal MCV. This is called a "masked" iron deficiency.
Key Laboratory Findings
- Low serum ferritin, with a level of <15 μg/L being highly specific for iron deficiency 1
- Low transferrin saturation
- Elevated total iron binding capacity (TIBC)
- Low serum iron
Treatment Considerations
Treatment involves oral iron supplementation, typically ferrous sulfate, and addressing the underlying cause of iron deficiency, such as blood loss or malabsorption, is also essential for effective treatment. It is crucial to consider the serum markers of iron deficiency, including low ferritin, low transferrin saturation, and raised total iron-binding capacity, to confirm the diagnosis, as the specificity of MCV for iron deficiency is limited 1.
From the Research
Iron Deficiency Anemia with Normocytic MCV
- Iron deficiency anemia is typically characterized by microcytic anemia, which is defined as the presence of small, often hypochromic, red blood cells in a peripheral blood smear and is usually characterized by a low MCV (less than 83 micron 3) 2.
- However, the laboratory evaluation of anemia begins with a complete blood count and reticulocyte count, and the anemia is then categorized as microcytic, macrocytic or normocytic, with or without reticulocytosis 3.
- Normocytic anemia can have various causes, including normocytic megaloblastic anemia and the acquired immunodeficiency syndrome 3.
- While iron deficiency is the most common cause of microcytic anemia, there is no direct evidence in the provided studies to suggest that iron deficiency anemia cannot occur with normocytic MCV.
- The diagnosis of iron deficiency anemia is typically confirmed by measurement of serum ferritin, iron concentration, transferrin saturation and iron-binding capacity, and, more recently, serum transferrin receptors 2.
Diagnosis and Evaluation
- The laboratory evaluation of anemia, including complete blood count, reticulocyte count, and examination of the peripheral smear, can help diagnose and categorize anemia 3.
- Specific tests, such as serum iron level, total iron-binding capacity, serum ferritin level, and hemoglobin electrophoresis, can help separate the microcytic anemias and diagnose iron deficiency anemia 2, 3.