How is the severity of anemia determined and managed?

Determination and Management of Anemia Severity

The severity of anemia is determined by specific hemoglobin thresholds based on age, sex, and physiological status, with management strategies tailored to the underlying cause, severity level, and patient characteristics. 1

Diagnostic Criteria for Anemia

Hemoglobin Thresholds

• Adults:
  • Men: < 13.0 g/dL 1, 2
  • Non-pregnant women: < 12.0 g/dL 1, 2
  • Pregnant women: < 11.0 g/dL 1
• Special populations:
  • Chronic Kidney Disease (CKD): < 13.5 g/L in males, < 12.0 g/L in females 3

Severity Classification

Anemia severity can be categorized based on hemoglobin levels:

Severity	General Population	Fetal Anemia (MoM)
Mild	10-12 g/dL	0.83-0.65
Moderate	8-10 g/dL	0.64-0.55
Severe	< 8 g/dL	< 0.55

Note: Fetal anemia is classified using multiples of the median (MoM) for gestational age 3

Diagnostic Workup

Essential Laboratory Tests

1. Complete Blood Count (CBC) - Baseline assessment
2. Iron studies:
   • Serum ferritin (most sensitive test for iron deficiency)
   • Transferrin saturation
   • C-reactive protein (to assess inflammatory status) 1
3. Additional tests based on clinical suspicion:
   • Vitamin B12 and folate levels
   • Reticulocyte count
   • Peripheral blood smear
   • Hemolysis markers (LDH, haptoglobin, bilirubin)

Differential Diagnosis Based on Laboratory Parameters

Parameter	Iron Deficiency	Anemia of Chronic Disease	Thalassemia
MCV	Low (<80 fL)	Low or normal	Very low
Serum Ferritin	Low (<15 μg/L)	Normal or high (>100 μg/L)	Normal
Transferrin Saturation	Low	Low	Normal
RDW	Elevated	Normal or slightly elevated	Normal

Management Strategies by Anemia Type

Iron Deficiency Anemia

1. Oral iron supplementation:

   • First-line therapy: Ferrous sulfate 200 mg twice daily
   • Continue for 3 months after hemoglobin normalizes 1
   • Add ascorbic acid (250-500 mg twice daily) to enhance absorption

2. Intravenous iron therapy when:

   • Inadequate response to oral iron (Hb increase <1.0 g/dL after 14 days)
   • Malabsorption conditions (inflammatory bowel disease)
   • Severe anemia requiring rapid correction 1

Vitamin B12 Deficiency Anemia

1. Parenteral vitamin B12 for pernicious anemia:

   • Initial: 100 mcg daily for 6-7 days (intramuscular or deep subcutaneous)
   • If clinical improvement: 100 mcg on alternate days for 7 doses
   • Maintenance: 100 mcg monthly for life 4
   • Avoid intravenous route (results in vitamin loss through urine)

2. Oral B12 supplementation:

   • For patients with normal intestinal absorption
   • Consider after initial parenteral treatment 4

Anemia in Chronic Kidney Disease

1. Regular screening:

   • At least yearly in all CKD patients
   • More frequent monitoring in diabetic patients (higher anemia prevalence) 3

2. Treatment options:

   • Intravenous iron can increase hemoglobin by 1.8 g/dL on average, even without erythropoietin 1
   • Erythropoiesis-stimulating agents (ESAs) for persistent anemia despite iron repletion

Anemia in Liver Disease/Hepatitis C

1. During antiviral therapy:
   • Monitor for hemolytic anemia (common with ribavirin)
   • Consider ribavirin dose reduction when Hb <10 g/dL
   • Consider erythropoietin when symptoms persist despite dose reduction
   • Transfusion for severe anemia (Hb <7.5 g/dL) or hemodynamic instability 3

Fetal Anemia

1. Screening and diagnosis:

   • Middle cerebral artery peak systolic velocity (MCA-PSV) is the primary screening technique
   • Fetal blood sampling for definitive diagnosis 3

2. Management:

   • Refer to centers with expertise in invasive fetal therapy when severe anemia is suspected
   • Intrauterine transfusion for severe anemia
   • Delivery at 37-38 weeks for pregnancies with significant risk of fetal anemia 3

Monitoring Response to Treatment

1. Repeat CBC in 2-4 weeks to assess response to therapy
2. Target response:
   • Hemoglobin rise ≥10 g/L within 2 weeks indicates good response to iron therapy 1
   • For vitamin B12 deficiency: reticulocyte response followed by normalization of hematologic values 4
3. Monthly monitoring of hemoglobin and iron studies during treatment

Common Pitfalls to Avoid

1. Diagnostic pitfalls:

   • Relying solely on MCV or MCH without confirming iron status
   • Misinterpreting ferritin levels in inflammatory states (ferritin is an acute phase reactant) 1
   • Failing to investigate underlying causes of anemia

2. Treatment pitfalls:

   • Excessive iron supplementation in conditions with elevated ferritin
   • Excessive ESA use (increases risk of death, MI, stroke, and thromboembolism) 1
   • Initiating EPO therapy in patients with very high endogenous erythropoietin levels (>500 IU/L) 3

3. Monitoring pitfalls:

   • Inadequate follow-up to detect evolving conditions
   • Failure to continue iron supplementation after hemoglobin normalization to replenish stores

By systematically evaluating hemoglobin levels, identifying the underlying cause, and implementing appropriate treatment strategies based on anemia type and severity, clinicians can effectively manage anemia and improve patient outcomes.