What is the initial workup and treatment for a patient with suspected anemia?

Initial Workup and Treatment for Suspected Anemia

The initial workup for suspected anemia should include a complete blood count (CBC), iron studies (serum ferritin, iron levels, total iron-binding capacity, transferrin saturation), vitamin B12 and folate levels, and reticulocyte count, followed by treatment based on the specific cause identified. 1

Diagnostic Approach

Step 1: Laboratory Assessment

• Complete blood count (CBC) with red cell indices 1, 2
• Iron studies:
  • Serum ferritin (primary marker for tissue iron stores)
  • Serum iron
  • Total iron-binding capacity (TIBC)
  • Transferrin saturation 1
• Vitamin B12 and folate levels 3, 2
• Reticulocyte count 1, 2
• Additional tests based on clinical suspicion:
  • Peripheral blood smear
  • Lactate dehydrogenase (LDH)
  • Haptoglobin
  • Bilirubin 2

Step 2: Classification Based on MCV

• Microcytic (MCV < 80 fL): Consider iron deficiency, thalassemia, anemia of chronic disease
• Normocytic (MCV 80-100 fL): Consider anemia of chronic disease, acute blood loss, renal disease
• Macrocytic (MCV > 100 fL): Consider vitamin B12/folate deficiency, liver disease, alcoholism 1, 2

Step 3: Specific Diagnostic Criteria

• Iron deficiency anemia:
  • Ferritin < 30 μg/L (highly specific at < 15 μg/L)
  • Low serum iron
  • High TIBC
  • Transferrin saturation < 15% 1
• Anemia of chronic disease:
  • Ferritin > 100 μg/L
  • Low serum iron
  • Low/normal TIBC
  • Transferrin saturation < 20% 1, 4
• B12 deficiency:
  • Low serum B12 levels
  • Macrocytic anemia 3

Treatment Algorithm

Iron Deficiency Anemia

1. First-line treatment: Oral iron supplementation

   • Ferrous sulfate 200 mg three times daily 1
   • Continue treatment for 3-6 months to replenish iron stores
   • Monitor hemoglobin response (should increase by ≥10 g/L within 2 weeks) 1

2. If inadequate response or intolerance to oral iron:

   • Switch to intravenous iron 5, 1, 6
   • Particularly indicated in:
     • Inflammatory bowel disease with active inflammation 5
     • Malabsorption conditions
     • Severe anemia 6

Vitamin B12 Deficiency

1. For pernicious anemia:

   • Parenteral vitamin B12 (100 mcg daily for 6-7 days)
   • Then 100 mcg on alternate days for seven doses
   • Then every 3-4 days for 2-3 weeks
   • Maintenance: 100 mcg monthly for life 3

2. For patients with normal intestinal absorption:

   • Oral B12 supplementation after initial parenteral treatment 3

Anemia of Inflammation/Chronic Disease

1. Treat the underlying inflammatory condition 4
2. Consider combination of iron therapy and erythropoiesis-stimulating agents in selected cases 4

Special Considerations

Inflammatory Bowel Disease

• Treat active inflammation to enhance iron absorption 5
• Use IV iron in patients with active inflammation and compromised absorption 5

Chronic Kidney Disease

• Monitor hemoglobin at least every three months if GFR < 30 ml/min per 1.73 m² 5
• Complete workup for anemia if hemoglobin < 12 g/dl in women or < 13 g/dl in men 5
• Treat iron deficiency if identified 5
• Consider erythropoietin or analogue if anemia persists despite iron therapy 5
• Monitor BP with each erythropoietin dose 5

Portal Hypertensive Gastropathy

• Start with oral iron supplements
• Switch to IV iron if ongoing bleeding with inadequate response to oral therapy 5

Monitoring and Follow-up

• Monitor hemoglobin and complete blood count every 3 months for the first year 1
• Check iron studies at each follow-up 1
• Annual monitoring after the first year unless risk factors are present 1
• More frequent monitoring (every 3 months) if risk factors present 1

Common Pitfalls to Avoid

1. Missing concurrent deficiencies: Check both iron and B12/folate levels, as deficiencies can coexist 3, 2

2. Overlooking inflammation: In inflammatory conditions, ferritin up to 100 μg/L may still indicate iron deficiency 1, 4

3. Inadequate follow-up: Failure to monitor response can miss persistent or recurrent anemia 1

4. Masking B12 deficiency: High-dose folic acid can correct the hematologic manifestations of B12 deficiency while allowing neurologic damage to progress 3

5. Premature discontinuation of therapy: Iron therapy should continue for months after hemoglobin normalizes to replenish stores 1, 6