Anemia Types: Comparison Chart for Diagnosis and Management
Classification by MCV (Mean Corpuscular Volume)
MICROCYTIC ANEMIA (MCV <80 fL)
| Type | Key Diagnostic Features | Treatment |
|---|---|---|
| Iron Deficiency Anemia | • Ferritin <30 ng/mL • Transferrin saturation <15% • Low serum iron, high TIBC [1,2] |
• Oral iron supplementation (first-line) • Parenteral iron if oral not tolerated/absorbed • Treat underlying cause (GI bleeding, malabsorption) [3] |
| Anemia of Chronic Disease | • Ferritin normal/elevated • Low serum iron, low/normal TIBC • Elevated CRP • Associated with cancer, infection, inflammation [1,2] |
• Treat underlying disease • Consider ESAs if symptomatic • IV iron for functional iron deficiency [1,4] |
| Thalassemia | • Family history • Microcytosis disproportionate to anemia • Normal/elevated ferritin • Hemoglobin electrophoresis abnormal [1,2] |
• Transfusion support for severe cases • Iron chelation if transfusion-dependent • Luspatercept for beta-thalassemia [5] |
| Lead Poisoning | • Occupational/environmental exposure • Basophilic stippling on smear • Elevated blood lead level [2] |
• Remove exposure source • Chelation therapy if indicated |
| Sideroblastic Anemia (Genetic) | • Ring sideroblasts on bone marrow • Elevated ferritin, increased TSAT • Specific gene mutations (ALAS2, SLC25A38, etc.) [1] |
ALAS2 defects (XLSA): Pyridoxine (vitamin B6) trial, transfusions, iron chelation [1] SLC25A38 defects: HSCT (curative), transfusions + chelation [1] ABCB7 defects: No treatment needed (mild) [1] |
NORMOCYTIC ANEMIA (MCV 80-100 fL)
The reticulocyte count is critical for distinguishing mechanisms 2, 6:
| Type | Reticulocyte Count | Key Features | Treatment |
|---|---|---|---|
| Acute Hemorrhage | High (>2%) | • Recent blood loss • Hemodynamic instability possible [1,2] |
• Stop bleeding source • Crystalloid resuscitation • Transfusion if severe/ongoing bleeding with instability [7] |
| Hemolytic Anemia | High (>2%) | • Jaundice, splenomegaly • Elevated indirect bilirubin • Low haptoglobin • Positive Coombs test (if autoimmune) [8,7] |
• Treat underlying cause • Corticosteroids for AIHA • Eculizumab for PNH [8] |
| Anemia of Chronic Disease | Low/Normal (<2%) | • Cancer, chronic infection, inflammation • Elevated ferritin, low iron • Elevated CRP [1,6] |
• Treat underlying condition • ESAs if symptomatic (with caution in cancer) • IV iron for functional deficiency [1,4] |
| Chronic Kidney Disease | Low/Normal (<2%) | • Elevated creatinine, low GFR • EPO deficiency [6,7] |
• ESAs individualized (not until Hb <10 g/dL if asymptomatic) • IV iron if functional deficiency [7] |
| Bone Marrow Failure | Low/Normal (<2%) | • Pancytopenia • Bone marrow biopsy showing hypocellularity [1,2] |
• Supportive transfusions • Immunosuppression or HSCT for aplastic anemia [7] |
MACROCYTIC ANEMIA (MCV >100 fL)
| Type | Key Diagnostic Features | Treatment |
|---|---|---|
| Vitamin B12 Deficiency | • Low serum B12 • Elevated methylmalonic acid • Neurologic symptoms possible • Megaloblastic changes on smear [1,2] |
• Oral or IM B12 supplementation • Treat underlying cause (pernicious anemia, malabsorption) |
| Folate Deficiency | • Low serum/RBC folate • Normal methylmalonic acid • Megaloblastic changes [1,2] |
• Oral folate supplementation • Identify dietary insufficiency or malabsorption |
| Myelodysplastic Syndrome | • Dysplastic changes on bone marrow • Cytopenias • Ring sideroblasts may be present [2,8] |
• Luspatercept for MDS with ring sideroblasts [5] • Azacitidine for high-risk MDS • Lenalidomide for 5q- MDS [8] |
| Medication-Induced | • Hydroxyurea, methotrexate, phenytoin exposure • History of chemotherapy [1,2] |
• Discontinue offending agent if possible • Supportive care |
| Hypothyroidism | • Elevated TSH • Low free T4 [2] |
• Thyroid hormone replacement |
| Alcohol-Related | • Chronic alcohol use • Elevated MCV without megaloblastic changes • May have liver disease [1] |
• Alcohol cessation • Nutritional supplementation (folate, thiamine) |
Initial Diagnostic Algorithm
For ALL anemia cases, obtain 2, 6:
- Complete blood count with MCV
- Reticulocyte count (corrected for anemia severity)
- Peripheral blood smear review
- Serum ferritin and transferrin saturation
- C-reactive protein (to assess inflammation)
Then stratify by MCV and reticulocyte count as shown above.
Critical Management Principles
Transfusion Thresholds
Limit red cell transfusions to severe symptomatic anemia 7. Avoid liberal transfusion strategies unless active bleeding with hemodynamic compromise.
ESA Use in Cancer-Related Anemia
Use ESAs cautiously and only in chemotherapy-induced anemia when Hb <10 g/dL 1. Do not use in cancer patients not receiving chemotherapy due to mortality concerns. Target Hb should not exceed 12 g/dL 1.
Iron Supplementation
For functional iron deficiency (normal/high ferritin but low transferrin saturation), use IV iron rather than oral 1, 4. Oral iron is first-line only for true iron deficiency anemia 3.
Genetic Anemias Requiring Specialist Referral
All sideroblastic anemias, thalassemias, and hereditary hemolytic anemias require hematology consultation 1. HSCT is curative for severe congenital sideroblastic anemia (SLC25A38 defects) 1.
Common Pitfalls to Avoid
- Do not assume microcytic anemia is always iron deficiency—check ferritin and consider thalassemia, especially if ferritin is normal/elevated 2
- Do not screen asymptomatic men or postmenopausal women for iron deficiency—if found, perform GI endoscopy to find source 3
- Do not overlook functional iron deficiency in chronic disease—normal ferritin does not exclude iron-restricted erythropoiesis 1, 4
- Do not use ESAs liberally in cancer patients—follow strict FDA/guideline restrictions 1
- In normocytic anemia, always check reticulocyte count—this distinguishes production failure from destruction/loss 2, 6, 7