From the Guidelines
Low MCV is indicated for further investigation, including ferritin testing, to determine the underlying cause of microcytic anemia. When a patient presents with low MCV, it suggests microcytic anemia, and ferritin testing is often recommended as part of the diagnostic workup to determine if iron deficiency is the underlying cause 1. According to the British Society of Gastroenterology guidelines, serum ferritin (SF) is the most specific test for iron deficiency in the absence of inflammation, and an SF level of <15 μg/L is indicative of absent iron stores 1.
Key points to consider in the diagnostic workup include:
- Microcytosis and hypochromia lose sensitivity for iron deficiency in the presence of chronic disease, thalassaemia, or vitamin B12/folate deficiency 1
- The specificity of MCV and MCH for iron deficiency is limited, as microcytosis and hypochromia also occur in many haemoglobinopathies and in some cases of anaemia of chronic disease 1
- An SF cut-off of 45 μg/L has been suggested as providing the optimal trade-off between sensitivity and specificity for iron deficiency in practice 1
In clinical practice, when a patient has low MCV, physicians should order ferritin along with other iron studies to determine if iron deficiency is the underlying cause, and to guide appropriate treatment, such as iron supplementation 1.
From the Research
Low MCV and Ferritin
- Low MCV (Mean Corpuscular Volume) is often associated with microcytic anemia, which can be caused by iron deficiency anemia 2, 3.
- Iron deficiency anemia is characterized by a low MCV, typically less than 83 micron 3 2 or less than 80 mcm3 in adults 3.
- Serum ferritin is a key indicator of iron stores in the body, and low ferritin levels can indicate iron deficiency anemia 2.
- A low MCV in the presence of low ferritin levels can suggest iron deficiency anemia, which can be managed with oral or intravenous iron supplementation 2, 3.
- However, a low MCV can also be caused by other conditions, such as thalassemia, sideroblastic anemia, and sickle cell anemia, which may require different treatments 3.