From the Guidelines
Microcytic anemia is primarily caused by genetic disorders of iron metabolism or heme synthesis, excluding common causes such as iron deficiency, thalassemias, and anemia of chronic disease. The causes of microcytic anemia can be complex and varied, but recent studies have shed light on the genetic disorders that lead to these conditions 1.
Key Causes
- Genetic disorders of iron metabolism, such as defects in the TMPRSS6 gene, can lead to microcytic anemia 1
- Heme synthesis disorders, such as sideroblastic anemia, can also cause microcytic anemia 1
- Other genetic disorders, such as defects in the STEAP3 and XLDPP genes, can also lead to microcytic anemia 1
Diagnostic Approach
- A diagnostic flowchart can be used to identify the underlying cause of microcytic anemia, including genetic disorders of iron metabolism or heme synthesis 1
- Laboratory tests, such as serum ferritin and transferrin saturation (TSAT), can help diagnose genetic disorders of iron metabolism 1
- Family history and clinical presentation, including features such as neurologic disease and skin photosensitivity, can also be indicative of genetic disorders of iron metabolism or heme synthesis 1
Importance of Accurate Diagnosis
- Accurate and timely diagnosis of genetic disorders of iron metabolism or heme synthesis is crucial to avoid unnecessary delay in diagnosis, invasive or costly diagnostic tests, and harmful treatments 1
- Unrecognized tissue iron loading can lead to severe morbidity and even mortality, underscoring the need for accurate diagnosis of these disorders 1
From the Research
Causes of Microcytic Anemia
The causes of microcytic anemia can be categorized into acquired and congenital causes. The most common cause of microcytic anemia is iron deficiency anemia, which can be managed with oral or intravenous iron, depending on the severity and comorbid conditions of the affected individual 2, 3.
- Iron deficiency anemia: This is the most common type of microcytic anemia and can be caused by disruptions in iron balance, such as menstruation, pregnancy, and gastrointestinal bleeding 2, 4, 5.
- Thalassemia: This is a genetic disorder that affects the production of hemoglobin, leading to microcytic anemia 3, 4, 6.
- Anemia of chronic disease: This type of anemia is caused by chronic diseases such as inflammation, infection, or cancer, and can lead to microcytic anemia 4, 5.
- Sideroblastic anemia: This is a rare type of anemia characterized by the presence of ringed sideroblasts in the bone marrow, leading to microcytic anemia 3, 4.
- Lead toxicity: This can cause microcytic anemia by inhibiting the production of hemoglobin 4.
Diagnosis and Evaluation
The diagnosis of microcytic anemia typically involves a complete blood count (CBC) and measurement of serum ferritin levels 2, 4, 5.
- Serum ferritin measurement is the first laboratory test recommended in the evaluation of microcytosis, with low ferritin levels suggesting iron deficiency 4.
- Further evaluation may include total iron-binding capacity, transferrin saturation level, serum iron level, and possibly hemoglobin electrophoresis 4, 5.
- A new formula based on low hemoglobin density (LHD) and microcytic anemia factor (MAF) has been developed to differentiate between thalassemia trait and iron deficiency anemia, with high sensitivity and specificity 6.