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

Initial Workup and Treatment for Suspected Anemia

The initial workup for anemia should include a complete blood count (CBC) with indices, reticulocyte count, peripheral blood smear examination, iron studies (ferritin, transferrin saturation, TIBC), and inflammatory markers to determine the underlying cause. 1

Diagnostic Thresholds

• Anemia is defined as hemoglobin concentrations below:
  • Males: <13.5 g/dL
  • Females: <12.0 g/dL 1

Initial Evaluation Algorithm

1. Complete Blood Count (CBC) with indices

   • MCV classification:
     • Microcytic (MCV <80 fL)
     • Normocytic (MCV 80-100 fL)
     • Macrocytic (MCV >100 fL) 1

2. Reticulocyte count

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

3. Iron studies

   • Serum ferritin
   • Transferrin saturation
   • Total iron binding capacity (TIBC) 1

4. Additional tests based on MCV classification:

   • Microcytic anemia:
     • Iron studies (ferritin <30 μg/L indicates iron deficiency)
     • Hemoglobin electrophoresis (if thalassemia suspected)
   • Normocytic anemia:
     • Inflammatory markers (ESR, CRP)
     • Renal function tests
     • Thyroid function tests
   • Macrocytic anemia:
     • Vitamin B12 and folate levels
     • Liver function tests
     • Reticulocyte count 1, 2

Differential Diagnosis Based on Classification

Microcytic Anemia

• Iron deficiency anemia
• Thalassemia
• Anemia of chronic disease (can be microcytic or normocytic)
• Sideroblastic anemia 1

Normocytic Anemia

• Acute blood loss
• Hemolytic anemia
• Anemia of chronic disease/inflammation
• Aplastic anemia
• Renal disease 1, 2

Macrocytic Anemia

• Vitamin B12 deficiency
• Folate deficiency
• Liver disease
• Alcoholism
• Myelodysplastic syndrome 1, 2

Key Distinguishing Features

Parameter	Iron Deficiency Anemia	Anemia of Chronic Disease
MCV	Low (microcytic)	Normal
Serum iron	Low	Low
TIBC	High	Low/Normal
Ferritin	< 30 μg/L	> 100 μg/L
Transferrin saturation	< 15%	< 20%

Treatment Approach

Iron Deficiency Anemia

1. Oral iron supplementation

   • Ferrous sulfate 325 mg daily or on alternate days
   • Continue for 3-6 months after hemoglobin normalization to replenish stores 1
   • Monitor response with repeat CBC in 2-4 weeks

2. Parenteral iron therapy when:

   • Oral iron not tolerated
   • Malabsorption present
   • Ongoing blood loss exceeds oral replacement capacity 3

Vitamin B12 Deficiency

1. Pernicious anemia

   • Parenteral vitamin B12 is the recommended treatment (lifelong)
   • Initial dose: 100 mcg daily for 6-7 days (IM or deep subcutaneous)
   • Maintenance: 100 mcg monthly for life 4

2. Normal intestinal absorption

   • Oral B12 supplementation for maintenance after initial parenteral treatment 4

Anemia of Chronic Disease

1. Treat underlying inflammatory condition rather than focusing solely on iron supplementation 1
2. Iron supplementation only if concurrent iron deficiency is confirmed 1
3. Consider erythropoiesis-stimulating agents (ESAs) if inadequate response to iron alone
   • Target Hb of 10-11 g/dL
   • Monitor Hb every 2-4 weeks initially, then monthly 1

Special Considerations

High-Risk Populations

• Women (menstruating or pregnant)
• Athletes (especially female runners)
• Vegetarians/vegans
• Patients with GI surgery (especially bariatric surgery)
• Patients with inflammatory conditions (e.g., IBD) - require more frequent monitoring 1

Monitoring Requirements

• For patients with GFR <30 ml/min per 1.73 m², hemoglobin should be checked at least every three months 5
• For patients with inflammatory conditions, monitor every 3 months 1

Potential Pitfalls

• Misdiagnosing ACD as iron deficiency - check MCV and TIBC carefully
• Failure to investigate underlying cause - especially in men and postmenopausal women with iron deficiency anemia
• ESA risks - increased risk of venous thromboembolism (1.5-fold)
• Transfusion risks - alloimmunization, volume overload, and iron overload with repeated transfusions 1

Remember that anemia is often a symptom of an underlying disorder that requires diagnosis and treatment, not just correction of the hemoglobin level.