Can you have a normal Complete Blood Count (CBC) but still have low ferritin levels?

Normal CBC with Low Ferritin: Understanding Hypoferritinemia Without Anemia

Yes, you can absolutely have a normal Complete Blood Count (CBC) but still have low ferritin levels, a condition known as Hypoferritinemia Without Anemia (HWA). This is an important clinical entity that is often overlooked in routine medical practice.

What is Hypoferritinemia Without Anemia?

Hypoferritinemia Without Anemia (HWA) is characterized by:

• Low serum ferritin levels (<30 μg/L)
• Normal CBC parameters (normal hemoglobin, hematocrit, RBC count, MCV, MCH, MCHC)
• Absence of anemia by definition

This condition represents the earliest stage of iron depletion, where iron stores are reduced but not yet to the point of affecting red blood cell production 1.

Diagnostic Considerations

Laboratory Parameters

• Ferritin: The primary marker of iron stores

  • Target ferritin level should be at least 50-100 μg/L to fully replenish iron stores 2
  • In inflammatory states, a higher cutoff (up to 100 μg/L) may be needed to diagnose iron deficiency 2

• CBC Parameters: May be entirely normal in HWA

  • Normal hemoglobin, hematocrit, MCV, MCH, MCHC
  • CBC parameters alone have poor discriminating power for iron deficiency without anemia 3

Clinical Significance

Low ferritin without anemia is not merely a laboratory finding but a clinical entity that can cause significant symptoms:

• Fatigue
• Weakness
• Depressed mood
• Hair loss
• Exercise intolerance
• Difficulty concentrating
• Restless legs syndrome
• Pica 1, 4

Progression of Iron Deficiency

Iron deficiency progresses through several stages:

1. Depleted iron stores (HWA): Low ferritin with normal CBC
2. Iron-deficient erythropoiesis: Low ferritin, normal hemoglobin, but changes in iron transport (low transferrin saturation)
3. Iron deficiency anemia: Low ferritin, low hemoglobin, microcytosis, hypochromia 4

Common Causes of Isolated Low Ferritin

• Menstrual blood loss in women of reproductive age
• Occult gastrointestinal blood loss
• Malabsorption disorders (celiac disease, post-bariatric surgery)
• Inadequate dietary iron intake
• Pregnancy or recent childbirth
• Chronic inflammatory conditions (may have functional iron deficiency despite normal or elevated ferritin) 2, 4

Clinical Implications

1. Don't dismiss normal CBC: A normal CBC does not exclude iron deficiency

   • Ferritin testing should be included when evaluating symptoms like fatigue, even with normal CBC 2

2. Avoid common pitfalls:

   • Premature discontinuation of iron supplementation before stores are fully replenished (ferritin >50 μg/L)
   • Failing to investigate underlying causes of iron deficiency
   • Overlooking inflammation which can falsely elevate ferritin 2

3. Treatment considerations:

   • Oral iron supplementation (ferrous sulfate 325 mg daily or on alternate days)
   • Continue treatment until ferritin levels reach at least 50-100 μg/L
   • Monitor ferritin after 8-10 weeks of treatment 2, 4

Special Populations

• Women of reproductive age: Higher risk due to menstrual losses; may require more aggressive supplementation 2
• Patients with chronic inflammatory conditions: May have functional iron deficiency despite normal or elevated ferritin 2
• Patients with thalassemia: May have normal ferritin but low MCV 5

Remember that HWA is a distinct clinical entity from iron deficiency anemia and requires recognition and appropriate management to prevent progression to anemia and to address associated symptoms 1.