What is the workup for microcytic, normochromic anemia?

From the Guidelines

The workup of microcytic, normochromic anemia should begin with a complete blood count (CBC) with peripheral smear, iron studies (serum iron, total iron binding capacity, ferritin), and hemoglobin electrophoresis, as recommended by the most recent guidelines 1.

Initial Evaluation

The initial evaluation of microcytic, normochromic anemia should include:

• Serum ferritin, which is the most specific test for iron deficiency in the absence of inflammation, with a level of <15 μg/L being indicative of absent iron stores 1
• Transferrin saturation, which can help distinguish between iron deficiency and other causes of microcytic anemia
• Reticulocyte count, which can help assess the severity of anemia and guide further testing
• Comprehensive metabolic panel to assess liver and kidney function

Further Testing

If iron deficiency is suspected, further testing may include:

• Stool for occult blood to identify potential sources of bleeding, especially in adults
• Upper and lower endoscopy to identify potential sources of bleeding
• Lead levels, particularly in children, to rule out lead poisoning as a cause of microcytic anemia
• Inflammatory markers like C-reactive protein and erythrocyte sedimentation rate to assess for anemia of chronic disease
• Bone marrow examination in some cases to rule out other causes of microcytic anemia

Diagnosis and Treatment

The diagnosis and treatment of microcytic, normochromic anemia depend on the underlying cause.

• Iron supplementation (typically ferrous sulfate 325mg three times daily) for iron deficiency 1
• Addressing chronic diseases for anemia of chronic inflammation
• Specific management for thalassemia, such as blood transfusions and iron chelation therapy It is essential to note that the distinction between microcytic normochromic and microcytic hypochromic anemia is crucial, as normochromic presentation may suggest early iron deficiency, thalassemia trait, or anemia of chronic disease rather than classic iron deficiency which typically presents as hypochromic 1.

From the Research

Workup of Microcytic Anemia

The workup of microcytic anemia involves several steps to determine the underlying cause of the condition.

• The laboratory evaluation of anemia begins with a complete blood count and reticulocyte count, as stated in the study 2.
• The anemia is then categorized as microcytic, macrocytic, or normocytic, with or without reticulocytosis.
• Examination of the peripheral smear and a small number of specific tests confirm the diagnosis.

Diagnostic Tests

Several diagnostic tests are used to evaluate microcytic anemia, including:

• Serum iron level
• Total iron-binding capacity
• Serum ferritin level
• Hemoglobin electrophoresis, as mentioned in the study 2
• Erythrocyte size-distribution width, which may be helpful in distinguishing iron deficiency from thalassemia minor, as stated in the study 2

Common Causes of Microcytic Anemia

The most common causes of microcytic anemia include:

• Iron deficiency anemia, which can be managed with oral or intravenous iron, depending on the severity and comorbid conditions of the affected individual, as mentioned in the study 3
• Thalassemia, a genetic disorder that affects the production of hemoglobin, as stated in the study 3
• Sideroblastic anemia, a rare disorder characterized by the accumulation of iron in the mitochondria of red blood cells, as mentioned in the study 4

Evaluation of Conventional Laboratory Parameters

The evaluation of conventional laboratory parameters, such as hemoglobin, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and mean corpuscular hemoglobin (MCH), can help differentiate between iron deficiency anemia and thalassemia, as stated in the study 5.

• In patients with iron deficiency anemia, these parameters are typically lower than in those with thalassemia.
• The red blood cell distribution width (RDW) may also be useful in discriminating between the different types of microcytic anemia, as mentioned in the study 5

Underuse of Laboratory Testing

The underuse of laboratory testing in the diagnostic workup of microcytic anemia is a significant issue, as highlighted in the study 6.

• Follow-up testing for iron deficiency was not performed in 34% of cases, and testing for thalassemia was not performed in 55% of cases with suspected thalassemia.
• The frequency of underuse of iron status and thalassemia/hemoglobinopathy testing decreased from group 1 to group 3, as stated in the study 6