Anemia Severity Classification
Anemia is classified as mild (hemoglobin 10-11.9 g/dl), moderate (hemoglobin 8-9.9 g/dl), and severe (hemoglobin <8 g/dl) according to established guidelines. 1
Standard Classification of Anemia Severity
Anemia is defined as a reduction of the hemoglobin (Hb) concentration, red blood cell count, or packed cell volume below normal levels. The severity classification is consistently defined across multiple guidelines:
- Mild anemia: Hb ≤11.9 g/dl and ≥10 g/dl
- Moderate anemia: Hb ≤9.9 g/dl and ≥8.0 g/dl
- Severe anemia: Hb <8.0 g/dl
This classification system is supported by multiple European Society for Medical Oncology (ESMO) guidelines 1, providing a consistent framework for evaluating anemia severity.
Alternative Grading System for Treatment-Related Anemia
For treatment-related anemia specifically, the National Cancer Institute's Common Toxicity Criteria of Adverse Events (CTCAE v3) uses a slightly different grading system 1:
- Grade 0: Hb within normal limits
- Grade 1: Hb from lower normal limit to 10.0 g/dl
- Grade 2: Hb 8.0 to <10.0 g/dl
- Grade 3: Hb 6.5 to <8.0 g/dl
- Grade 4: Hb <6.5 g/dl
- Grade 5: Death
Normal Hemoglobin Reference Ranges
It's important to note that the baseline definition of anemia according to the World Health Organization (WHO) is 2:
- Hemoglobin <12.0 g/dl in women
- Hemoglobin <13.0 g/dl in men
These thresholds serve as the starting point for determining whether anemia is present before classifying its severity.
Clinical Impact of Anemia Severity
The severity of anemia correlates with clinical outcomes:
- Anemia has a negative impact on quality of life and is a major contributor to cancer-related fatigue 1
- Severe anemia is associated with higher morbidity and mortality rates 3
- In acute coronary syndromes, moderate anemia (HR 1.40) and severe anemia (HR 1.67) are associated with significantly increased 30-day mortality 3
Prevalence by Severity Level
In cancer patients, the distribution of anemia severity is 1:
- Mild anemia: 30-39% of patients
- Moderate anemia: 9-14% of patients
- Severe anemia: 1% of patients
The prevalence increases with certain cancer types (lung 71%, gynecological 65%) and with the number of chemotherapy cycles 1.
Clinical Approach to Anemia
When evaluating anemia of any severity, a thorough diagnostic workup is essential to determine the underlying cause, which may include:
- Complete blood count with reticulocyte count
- Iron studies (serum iron, transferrin saturation, ferritin)
- Vitamin B12 and folate levels
- Assessment for occult blood loss
- Evaluation of renal function
- Peripheral blood smear examination
The severity classification guides treatment decisions, with more aggressive interventions typically required for moderate to severe anemia to prevent complications and improve quality of life.