How do I determine the type of anemia I have?

Determining the Type of Anemia

The most effective approach to determine the type of anemia is to perform a complete blood count (CBC) with indices, followed by targeted laboratory tests based on mean corpuscular volume (MCV) classification and reticulocyte count. 1

Initial Diagnostic Workup

Step 1: Complete Blood Count with Indices

• Confirm anemia based on hemoglobin levels:
  • Males: < 135 g/L (13.5 g/dL)
  • Females: < 120 g/L (12.0 g/dL) 2

Step 2: Classify Anemia Based on MCV and Reticulocyte Count

• MCV Classification:

  • Microcytic (MCV < 76 fl): Suggests iron deficiency or thalassemia
  • Normocytic (MCV normal): Suggests anemia of chronic disease or renal insufficiency
  • Macrocytic (MCV > 100 fl): Suggests B12/folate deficiency or medication effects 1

• Reticulocyte Count Assessment:

  • Low reticulocyte index: Indicates decreased production
  • High reticulocyte index: Suggests blood loss or hemolysis 1

Targeted Testing Based on Classification

For Microcytic Anemia:

1. Iron Studies:
   • Serum ferritin (< 30 μg/L indicates iron deficiency)
   • Serum iron (low in both iron deficiency and anemia of chronic disease)
   • Total iron-binding capacity (TIBC) (high in iron deficiency, low/normal in anemia of chronic disease)
   • Transferrin saturation (< 15% in iron deficiency) 1
2. Hemoglobin electrophoresis (if thalassemia suspected)

For Normocytic Anemia:

1. Renal function tests (BUN, creatinine, GFR)
2. Iron studies (to rule out mixed anemia)
3. Inflammatory markers (ESR, CRP)
4. Peripheral blood smear examination

For Macrocytic Anemia:

1. Vitamin B12 and folate levels
2. Liver function tests
3. Thyroid function tests
4. Medication review

Advanced Testing When Initial Workup Is Inconclusive

• Bone marrow examination (when diagnosis remains unclear)
• Hemolysis workup if suspected:
  • Lactate dehydrogenase (LDH)
  • Haptoglobin
  • Bilirubin
  • Direct Coombs test 1

Key Diagnostic Parameters Table

Parameter	Iron Deficiency Anemia	Anemia of Chronic Disease	B12/Folate Deficiency	Hemolytic Anemia
MCV	Low	Normal	High	Normal
Reticulocyte count	Low	Low	Low	High
Serum iron	Low	Low	Normal	Normal
TIBC	High	Low/Normal	Normal	Normal
Ferritin	< 30 μg/L	> 100 μg/L	Normal	Normal
Transferrin saturation	< 15%	< 20%	Normal	Normal

Important Considerations

• Hemoglobin is preferred over hematocrit for diagnosis as it is more reproducible across laboratories and less affected by sample storage conditions 2
• Peripheral blood smear examination provides valuable morphological information that can guide diagnosis 1
• In chronic kidney disease patients, anemia is often normochromic and normocytic, requiring evaluation of renal function 2
• Consider more frequent monitoring in patients with diabetes who have higher prevalence of anemia at earlier stages of CKD 2
• Abnormalities in multiple cell lines (white blood cells, red blood cells, platelets) warrant hematology consultation 2

Common Pitfalls to Avoid

• Don't rely solely on MCV for diagnosis - overlapping features can occur between different types of anemia
• Don't ignore inflammation's effect on ferritin - ferritin is an acute phase reactant and may be falsely elevated in inflammatory states
• Don't forget to check for blood loss - occult GI bleeding is a common cause of iron deficiency anemia
• Don't miss mixed anemias - multiple deficiencies can coexist (e.g., iron and B12 deficiency)
• Don't neglect medication review - many medications can cause or contribute to anemia

By following this systematic approach based on MCV classification and reticulocyte count, followed by targeted testing, you can efficiently determine the specific type of anemia and guide appropriate treatment.