From the Guidelines
In anemia of chronic disease, lab results typically show low hemoglobin and hematocrit, low serum iron and iron-binding capacity, normal or elevated ferritin, normal or slightly decreased red blood cell size (MCV), and elevated inflammatory markers (e.g., CRP, ESR). The key distinguishing feature is normal or elevated ferritin despite low iron levels, which occurs because chronic inflammation increases ferritin production as an acute phase reactant, even though iron stores may be low 1.
Key Laboratory Findings
- Low hemoglobin and hematocrit
- Low serum iron and iron-binding capacity
- Normal or elevated ferritin
- Normal or slightly decreased red blood cell size (MCV)
- Elevated inflammatory markers (e.g., CRP, ESR)
Other findings may include slightly elevated red cell distribution width (RDW) and normal or low reticulocyte count, indicating an inadequate bone marrow response to the anemia. To differentiate from iron deficiency anemia, additional tests like soluble transferrin receptor levels or bone marrow iron staining may be necessary in some cases 1. Understanding these lab patterns is crucial for proper diagnosis and management, as treatment focuses on addressing the underlying chronic condition rather than iron supplementation alone 1.
Diagnostic Criteria
In the presence of biochemical or clinical evidence of inflammation, the diagnostic criteria for anaemia of chronic disease are serum ferritin >100 μg/L and transferrin saturation <20% 1. If the serum ferritin level is between 30 and 100 μg/L, a combination of true iron deficiency and anaemia of chronic disease is likely. The distinction between iron deficiency anaemia and anaemia of chronic disease is important, as treatment is different between these conditions 1.
Importance of Inflammatory Status
The evaluation of anaemia in any given patient is always incomplete if the inflammatory status is not clearly defined 1. Measurements of inflammatory parameters that are independent of iron metabolism (ESR, CRP) should be carried out to aid diagnosis. Determination of the causal factors is not only of academic interest, but also essential for effective treatment, as treatment is possible only if the contributing factors in a particular patient are clearly defined 1.
From the Research
Laboratory Findings in Anemia of Chronic Disease
The laboratory findings in anemia of chronic disease are characterized by:
- Low serum iron levels despite adequate iron stores 2, 3, 4, 5
- Decreased serum transferrin and transferrin saturation 3
- Increased serum ferritin levels 3, 4, 5
- Increased reticuloendothelial iron stores 3, 5
- Elevated erythrocyte-free protoporphyrin 3
- Reduced iron absorption 3
- Normochromic, normocytic anemia in most cases, but hypochromic microcytic anemia in 30-50% of patients 2
- Low reticulocyte production 2
- Functional iron deficiency (iron-restricted erythropoiesis) in 20% of patients, leading to hypochromic microcytic anemia 6
- Increased hepcidin levels, which can help identify iron deficiency in patients with anemia of chronic disease 5
Diagnostic Markers
Diagnostic markers for anemia of chronic disease include:
- Serum iron and total iron-binding capacity (TIBC) 2, 3
- Transferrin saturation 3
- Serum ferritin 3, 4, 5
- Soluble transferrin receptor value and reticulocyte hemoglobin content 6
- Hepcidin levels 5
Differential Diagnosis
The differential diagnosis for anemia of chronic disease includes: