Diagnosis: Iron Deficiency Anemia
This patient has iron deficiency anemia, indicated by the low hemoglobin A2 concentration of 1.9% (absolute value approximately 194 mg/100mL), which falls well below the normal range and is characteristic of iron deficiency rather than thalassemia. 1
Diagnostic Reasoning
Hemoglobin A2 as a Discriminatory Test
The absolute hemoglobin A2 concentration is the key diagnostic feature here. With Hgb of 10.2 g/dL and HgbA2 of 1.9%, the calculated absolute HgbA2 is approximately 194 mg/100mL, which is significantly below the normal mean of 459 ± 60 mg/100mL. 1
Iron deficiency characteristically produces a mean absolute HgbA2 of 229 ± 58 mg/100mL, while beta-thalassemia minor shows elevated levels at 766 ± 99 mg/100mL. 1 This patient's value is consistent with iron deficiency.
The low HgbA2 percentage (<2.0%) effectively excludes beta-thalassemia trait, which would show HgbA2 >3.5% despite similar degrees of microcytic anemia. 1
Anemia Severity Classification
This represents mild anemia (Hgb 10.2 g/dL), defined as hemoglobin ≥10.0 g/dL and ≤11.9 g/dL. 2
The hemoglobin level is below the WHO-defined normal lower limit for women (Hgb <12.0 g/dL) and men (Hgb <13.0 g/dL). 2, 3
Management Approach
Immediate Workup Required
Measure serum ferritin, iron, total iron-binding capacity (TIBC), and transferrin saturation to confirm iron deficiency and assess severity. 4
In men with Hgb <12 g/dL and postmenopausal women with Hgb <10 g/dL, investigate more urgently for underlying causes including gastrointestinal malignancy. 2
Obtain complete blood count with red cell indices (MCV, MCH, MCHC) to confirm microcytosis, which is expected with both iron deficiency and would have been present to produce the low HgbA2. 1
Iron Replacement Therapy
Initiate oral or intravenous iron replacement based on severity of deficiency, patient tolerance, and clinical context. 4
Baseline and periodic monitoring of iron parameters (ferritin, transferrin saturation) is essential during treatment. 4
For functional iron deficiency (ferritin <100 mg/dL or transferrin saturation <20%), parenteral iron may be more effective than oral supplementation. 4
Source Investigation
Identify and address the underlying cause of iron deficiency: blood loss (gastrointestinal, menstrual), malabsorption (celiac disease, inflammatory bowel disease), or inadequate dietary intake. 3
Gastrointestinal evaluation (endoscopy, colonoscopy) is warranted in adults without obvious source, particularly in men and postmenopausal women. 2
Common Pitfalls to Avoid
Do not assume thalassemia trait based solely on mild anemia and microcytosis without checking HgbA2 levels. The low HgbA2 here confirms iron deficiency rather than thalassemia. 1
Do not initiate erythropoiesis-stimulating agents (ESAs) for simple iron deficiency anemia. ESAs are indicated only for chemotherapy-associated anemia or chronic kidney disease, not nutritional deficiency. 4
Do not overlook the need for source investigation. Even mild iron deficiency anemia may indicate significant underlying pathology including malignancy. 2