What is the cause of microcytic anemia with normal to elevated ferritin (iron storage protein) levels, specifically a ferritin level of 152?

From the Guidelines

Microcytic anemia with a ferritin level of 152 ng/mL is unlikely to be due to iron deficiency anemia, and other causes such as anemia of chronic disease or thalassemia should be considered. According to the British Society of Gastroenterology guidelines for the management of iron deficiency anemia in adults 1, a serum ferritin value above 150 μg/L is unlikely to occur with absolute iron deficiency, even in the presence of inflammation. This suggests that the patient's anemia is likely due to another cause.

Some possible causes of microcytic anemia with normal or elevated ferritin levels include:

• Anemia of chronic disease, which can occur in the context of chronic inflammatory processes, infection, or malignancy
• Thalassemia, a genetic disorder that affects the production of hemoglobin
• Sideroblastic anemia, a rare disorder characterized by the accumulation of iron in the mitochondria of red blood cell precursors

Further testing is recommended to determine the underlying cause of the anemia, including:

• Hemoglobin electrophoresis to evaluate for thalassemia 1
• Complete blood count with red cell indices to assess for other abnormalities in red blood cell morphology
• Reticulocyte count to evaluate the bone marrow's response to anemia
• Inflammatory markers like CRP or ESR to assess for underlying chronic inflammatory processes

Treatment should target the underlying cause of the anemia, rather than providing iron supplementation, which would be ineffective and potentially harmful since iron stores are already adequate 1. If anemia of chronic disease is confirmed, treating the underlying inflammatory condition is the primary approach, though in some cases erythropoiesis-stimulating agents might be considered for severe or symptomatic anemia. For thalassemia, management depends on the severity, ranging from observation for mild cases to transfusions for more severe forms.

From the Research

Microcytic Anemia with Normal Ferritin Levels

• Microcytic anemia 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.
• The most common cause of microcytic anemia is iron deficiency anemia, but a ferritin level of 152 suggests that iron deficiency may not be the primary cause in this case 2, 3, 4, 5.
• Other potential causes of microcytic anemia include thalassemia, anemia of chronic disease, and sideroblastic anemia 2, 3, 4, 5, 6.

Diagnostic Approach

• Serum ferritin measurement is the first laboratory test recommended in the evaluation of microcytosis, and a level of 152 is considered normal 4.
• Further evaluation may include total iron-binding capacity, transferrin saturation level, serum iron level, and possibly hemoglobin electrophoresis to differentiate between potential causes of microcytic anemia 3, 4, 5.
• Anemia of chronic disease is suggested with low iron levels and decreased total iron-binding capacity, while patients with beta-thalassemia trait usually have elevated levels of hemoglobin A2 4.

Potential Causes with Normal Ferritin Levels

• Thalassemia trait: characterized by elevated levels of hemoglobin A2 and a low MCV 4, 6.
• Anemia of chronic disease: suggested with low iron levels and decreased total iron-binding capacity 4.
• Sideroblastic anemia: characterized by the presence of ringed sideroblasts in the bone marrow 3.
• Other inherited causes of microcytic anemia, such as sickle cell anemia, may also be considered 6.