Iron Deficiency Without Anemia
This presentation represents iron deficiency without anemia (also called non-anemic iron deficiency), not iron deficiency anemia, since the hemoglobin is normal. 1
Diagnostic Interpretation
Your laboratory findings clearly indicate iron deficiency in the pre-anemic stage:
- Ferritin of 3 μg/L is highly specific for depleted iron stores (specificity 0.99 for values <15 μg/L) 1
- Elevated TIBC of 422 mg/dL reflects the body's attempt to capture more iron by increasing transferrin production 1
- Mildly low MCV and MCH indicate early microcytosis and hypochromia, which are red cell changes that accompany iron deficiency 1
- Elevated RDW is an indicator of iron deficiency, reflecting increased variation in red blood cell size as iron-deficient cells are produced alongside older normal cells 1, 2
- Normal hemoglobin means anemia has not yet developed 1
Understanding the Terminology
The correct diagnosis is "iron deficiency" or "non-anemic iron deficiency (NAID)," NOT "iron deficiency anemia." 1 The development of anemia from iron deficiency progresses through stages: first, body iron stores are depleted (causing low ferritin), then red cell indices change (low MCV/MCH, high RDW), and finally hemoglobin drops below normal thresholds 1.
Your patient is in the iron-deficient but not yet anemic stage. 1
Clinical Significance
- Investigation for underlying causes should still be considered even without anemia, particularly if there are other clinical concerns, though the overall prevalence of serious pathology (especially GI malignancy) is lower in non-anemic iron deficiency 1
- In premenopausal women without other concerning features, menstrual blood loss is the most likely cause and GI investigation is generally not warranted 1
- In men, postmenopausal women, or those with concerning symptoms, investigation should be pursued regardless of whether frank anemia has developed 1
Treatment Considerations
Iron supplementation is appropriate for documented iron deficiency even in the absence of anemia, as it can prevent progression to anemia and improve symptoms related to iron deficiency (fatigue, reduced exercise capacity) 1. Typical oral iron supplementation is 100-200 mg elemental iron daily 1.
Key Pitfall to Avoid
Do not dismiss iron deficiency simply because hemoglobin is normal. 1 The ferritin of 3 μg/L represents severely depleted iron stores that warrant both treatment and investigation for the underlying cause based on the patient's demographic and clinical context 1.