From the Guidelines
Iron Deficiency Anemia (IDA) and Thalassemia can be distinguished through key laboratory test differences.
Key Laboratory Test Differences
- Mean Cell Volume (MCV): IDA typically presents with microcytosis (low MCV), but this can also be seen in thalassemia, although the MCV is usually reduced out of proportion to the level of anemia in thalassemia 1.
- Mean Cell Hemoglobin (MCH): MCH is a more reliable marker of iron deficiency, and a reduction is seen in both absolute and functional iron deficiency (FID) 1.
- Red Cell Distribution Width (RDW): A low MCV with an RDW of greater than 14.0% indicates iron-deficiency anemia, whereas a low MCV with an RDW less than or equal to 14.0% indicates thalassemia minor 1.
- Serum Ferritin: Serum ferritin concentration is the most powerful test for IDA, with a level of <15 μg/L being highly specific for iron deficiency 1.
- Hb Electrophoresis: Recommended in those with microcytosis and normal iron studies, particularly if there is an appropriate ethnic background, to rule out thalassemia 1.
Diagnostic Approach
In patients with microcytic anemia, a combination of these laboratory tests can help differentiate between IDA and thalassemia. If the serum ferritin level is low (<15 μg/L), it is likely IDA 1. However, if the serum ferritin level is normal or elevated, and there is microcytosis, thalassemia should be considered, and Hb electrophoresis should be performed 1.
From the Research
Key Laboratory Test Differences
The key laboratory test differences between Iron Deficiency Anemia (IDA) and Thalassemia are:
- Red cell distribution width (RDW) Index: significant differences were observed between IDA and Thalassemia patients, with a sensitivity of 90% and specificity of 77% 2
- Green and King Index: demonstrated high diagnostic accuracy, with a sensitivity of 90% and specificity of 82% 2, 3
- England and Fraser Index: showed a sensitivity of 85% and specificity of 80%, with a large effect size 2
- Erythrocyte count (RBC): had excellent performances, especially when observed in adults and children 4
- Ferritin levels: can be used to differentiate between iron-deficiency anemia and thalassaemia carrier status 5
- Hemoglobin electrophoresis: can confirm or rule out thalassaemia 6, 5
Laboratory Parameters
Laboratory parameters that can help differentiate between IDA and Thalassemia include:
- Mean corpuscular volume (MCV): significant differences were observed between IDA and Thalassemia patients 2, 3
- Reticulocyte count: can help categorize anemia as microcytic, macrocytic or normocytic, with or without reticulocytosis 6
- Serum iron level: can help separate microcytic anemias 6
- Total iron-binding capacity: can help separate microcytic anemias 6
- Serum ferritin level: can help separate microcytic anemias 6
Diagnostic Indices
Several diagnostic indices have been proposed to simplify the differential diagnosis between IDA and Thalassemia, including:
- Green and King Index: demonstrated high diagnostic accuracy 2, 3
- RDW Index: significant differences were observed between IDA and Thalassemia patients 2
- England and Fraser Index: showed a sensitivity of 85% and specificity of 80% 2
- Ehsani index: had excellent performances, especially when observed in adults and children 4
- Wongprachum and Keikhaei indices: showed the best discriminatory power with Youden index values of 0.908 and 0.896, respectively 3