What is the approach to evaluating and managing anemia?

Comprehensive Approach to Evaluating and Managing Anemia

A systematic approach to anemia evaluation requires initial characterization by CBC with indices, followed by targeted testing based on MCV classification and reticulocyte count to determine the underlying cause and guide appropriate treatment.

Initial Assessment

Definition and Screening

• Anemia is defined as hemoglobin level of:
  • <135 g/L (13.5 g/dL) in adult males
  • <120 g/L (12.0 g/dL) in adult females 1
• A decrease of ≥2 g/dL from baseline should prompt evaluation even if values remain within normal range 1

Essential Initial Laboratory Tests

1. Complete Blood Count (CBC) with indices
2. Visual review of peripheral blood smear
3. Reticulocyte count/index
4. Iron studies (ferritin, iron, TIBC, transferrin saturation)

Morphologic Approach to Anemia Classification

1. Microcytic Anemia (MCV <80 fL)

• Common causes:
  • Iron deficiency anemia
  • Thalassemia
  • Anemia of chronic disease/inflammation
  • Sideroblastic anemia 1
• Additional tests:
  • Iron panel (ferritin, iron, TIBC, transferrin saturation)
  • Hemoglobin electrophoresis if thalassemia suspected

2. Normocytic Anemia (MCV 80-100 fL)

• Common causes:
  • Acute blood loss
  • Hemolysis
  • Anemia of chronic inflammation
  • Renal insufficiency
  • Bone marrow failure 1, 2
• Additional tests based on clinical suspicion:
  • LDH, haptoglobin, bilirubin (for hemolysis)
  • Creatinine, BUN (for renal function)
  • CRP or ESR (for inflammation)

3. Macrocytic Anemia (MCV >100 fL)

• Common causes:
  • Vitamin B12 deficiency
  • Folate deficiency
  • Alcoholism
  • Myelodysplastic syndrome
  • Medication effects (e.g., hydroxyurea, diphenytoin) 1
• Additional tests:
  • Vitamin B12 and folate levels
  • Thyroid function tests
  • Liver function tests

Kinetic Approach to Anemia

1. Low Reticulocyte Index (RI <1.0)

• Indicates decreased RBC production
• Common causes:
  • Iron, B12, or folate deficiency
  • Anemia of chronic inflammation
  • Bone marrow dysfunction
  • Aplastic anemia 1

2. Normal/High Reticulocyte Index (RI >2.0)

• Indicates blood loss or hemolysis
• Additional tests:
  • Stool occult blood test
  • LDH, haptoglobin, bilirubin
  • Direct antiglobulin test (Coombs) 1

Special Considerations for Specific Populations

Chronic Kidney Disease

• Anemia in CKD is typically normocytic, normochromic due to erythropoietin deficiency 3
• Significant increase in prevalence when GFR falls below 60 mL/min/1.73m² 3
• Monitor hemoglobin (preferred over hematocrit) at least yearly in CKD patients 1
• More frequent monitoring indicated in diabetic patients with CKD due to higher prevalence of anemia 1

Cancer and Chemotherapy-Induced Anemia

• Evaluate for anemia when Hb <11 g/dL or decrease of ≥2 g/dL from baseline 1
• Platinum-based regimens frequently cause anemia through combined bone marrow and kidney toxicity 1
• Risk increases with number of chemotherapy cycles 1

Management Principles

Iron Deficiency Anemia

• Absolute iron deficiency: ferritin <30 ng/mL and transferrin saturation <15% 1
• In non-dialysis CKD patients without known causes of iron loss, iron deficiency should prompt evaluation for GI bleeding 1

Anemia of Inflammation

• Characterized by iron sequestration due to hepcidin upregulation
• Features include hypoferremia and hyperferritinemia 4
• Treatment focuses on underlying inflammatory condition

Severe Symptomatic Anemia

• Red blood cell transfusions should be limited to patients with severe symptomatic anemia 2
• For acute blood loss, initial management includes crystalloid fluids and hemorrhage control 2

Common Pitfalls to Avoid

1. Incomplete evaluation: Failing to determine underlying cause before treatment
2. Overlooking mixed anemias: Multiple causes may coexist, especially in elderly patients
3. Misinterpreting ferritin: As an acute phase reactant, ferritin may be elevated despite iron deficiency in inflammatory states 1
4. Ignoring non-CKD causes: The presence of anemia in CKD patients doesn't necessarily mean it's solely due to erythropoietin deficiency 1
5. Missing occult bleeding: Iron deficiency in adults without obvious blood loss should prompt GI evaluation

By following this systematic approach to anemia evaluation and management, clinicians can efficiently identify the underlying cause and implement appropriate treatment strategies to improve patient outcomes.