Laboratory Findings in Anemia of Chronic Disease
The typical laboratory findings in anemia of chronic disease include normocytic normochromic anemia with low serum iron, low transferrin saturation (<20%), normal to elevated ferritin (30-100 μg/L in mixed picture, >100 μg/L in pure ACD), and low total iron binding capacity (TIBC). 1
Key Laboratory Parameters
Complete Blood Count
- Hemoglobin: Mild to moderate reduction (typically 8-10 g/dL)
- Hematocrit: Proportionally reduced
- MCV: Usually normal (normocytic) but can be microcytic in 30-50% of cases 2
- Red cell morphology: Normochromic, normocytic (occasionally hypochromic, microcytic)
- Reticulocyte count: Low or inappropriately normal (indicating underproduction) 1
Iron Studies
- Serum iron: Decreased
- Total iron-binding capacity (TIBC): Decreased
- Transferrin: Decreased
- Transferrin saturation: Reduced (<20%) 1
- Serum ferritin:
100 μg/L indicates pure anemia of chronic disease
- 30-100 μg/L suggests a combination of iron deficiency and anemia of chronic disease 3
Inflammatory Markers
- Elevated erythrocyte sedimentation rate (ESR)
- Elevated C-reactive protein (CRP)
- Elevated pro-inflammatory cytokines (IL-1, IL-6, TNF-alpha) 4
Other Relevant Parameters
- Elevated hepcidin levels (key mediator of iron sequestration)
- Normal to slightly elevated erythropoietin levels (but inadequate for degree of anemia)
- Bone marrow examination: Normal to increased iron stores in macrophages with decreased sideroblasts 1
Differentiating from Iron Deficiency Anemia
| Parameter | Anemia of Chronic Disease | Iron Deficiency Anemia |
|---|---|---|
| Serum iron | Low | Low |
| TIBC | Low or normal | High |
| Transferrin saturation | Low (<20%) | Very low (<15%) |
| Serum ferritin | Normal to high (>30 μg/L) | Low (<30 μg/L) |
| Reticulocyte hemoglobin | Moderately reduced | Significantly reduced (<27 pg/mL) [5] |
| Bone marrow iron | Present (in macrophages) | Absent |
Common Pitfalls in Laboratory Interpretation
- Ferritin is an acute phase reactant and may be elevated despite iron deficiency in inflammatory states
- In mixed anemia (ACD + iron deficiency), ferritin between 30-100 μg/L suggests both conditions 3
- Reticulocyte count should be interpreted in context of the degree of anemia
- Hemoglobin measurement is more reliable than hematocrit, which can be affected by sample storage conditions 3
- Newer parameters like reticulocyte hemoglobin content may help differentiate ACD from iron deficiency anemia with high accuracy (sensitivity 93.4%, specificity 95.83% at cutoff of 27 pg/mL) 5
Remember that anemia of chronic disease is the second most common type of anemia worldwide after iron deficiency anemia 6, and laboratory findings should always be interpreted in the context of the underlying chronic inflammatory, infectious, or neoplastic disorder.