Laboratory Interpretation and Management
This patient does NOT have anemia—the hemoglobin of 154 g/L is well above the WHO threshold of 130 g/L for men and 120 g/L for non-pregnant women, and the elevated MCHC (316 g/L) indicates hypochromia suggesting early iron deficiency without anemia, combined with mild leukocytosis that warrants investigation for underlying inflammation or infection. 1
Key Laboratory Findings
Hemoglobin and Hematocrit Status:
- Hemoglobin 154 g/L and hematocrit 0.49 are both normal to high-normal values, definitively excluding anemia by WHO criteria 1
- The RBC count of 5.64 × 10¹²/L is also within normal range 1
Iron Status Indicators:
- MCHC of 316 g/L indicates hypochromia (reduced hemoglobin concentration in red cells), which is a marker of iron deficiency that may be more reliable than MCV alone 1
- Iron saturation of 0.23 (23%) is borderline low, as transferrin saturation <20% typically indicates iron deficiency, though values between 20-25% warrant further evaluation 1
- This pattern suggests non-anemic iron deficiency (NAID)—depleted iron stores without yet developing anemia 1
Leukocytosis:
- WBC 12.3 × 10⁹/L with neutrophils 9.2 × 10⁹/L represents mild leukocytosis with neutrophilia, suggesting possible inflammation, infection, or physiologic stress 1
- This inflammatory state is clinically important because inflammation can mask iron deficiency by elevating ferritin levels (an acute phase reactant) 1
Diagnostic Approach
Essential Next Steps:
Obtain serum ferritin immediately as it is the single most useful marker for confirming iron deficiency 1
- Ferritin <15 μg/L is highly specific for iron deficiency (specificity 0.99) 1
- Ferritin <30 μg/L generally indicates low iron stores 1
- However, if ferritin is 30-100 μg/L in the context of inflammation (suggested by the leukocytosis), this may represent a "false-normal" ferritin masking true iron deficiency 1
- Ferritin <45 μg/L provides optimal sensitivity/specificity trade-off for iron deficiency, especially with concurrent inflammation 1
Calculate MCV (mean corpuscular volume) from the available data to assess for microcytosis, though MCH (mean corpuscular hemoglobin) would be more reliable if available 1
Investigate the cause of leukocytosis:
Management Strategy
If Iron Deficiency is Confirmed (ferritin <30-45 μg/L):
- In non-anemic iron deficiency without GI symptoms, investigation for GI pathology is generally NOT warranted, particularly in premenopausal women where menstrual losses are the likely cause 1
- However, the presence of leukocytosis changes this calculus—investigate for underlying chronic inflammatory conditions, infections, or occult malignancy that could explain both findings 1
Iron Supplementation:
- Oral iron therapy is first-line treatment: ferrous sulfate 324 mg (65 mg elemental iron) daily 3, 4
- Monitor response at 2 weeks: hemoglobin rise ≥10 g/L confirms iron deficiency even if initial iron studies were equivocal 1
- Continue supplementation to replete iron stores, not just correct hemoglobin 4
If Inflammation is Present (elevated CRP, persistent leukocytosis):
- Oral iron may be ineffective due to hepcidin-mediated blockade of iron absorption in inflammatory states 1, 2
- Consider intravenous iron if oral therapy fails or if there is evidence of functional iron deficiency with inflammation 1, 5
- Treat the underlying inflammatory condition as this is essential for effective iron utilization 1, 2, 6
Critical Pitfalls to Avoid
- Do not assume anemia is present—this patient's hemoglobin is normal; the issue is iron deficiency without anemia 1
- Do not ignore the leukocytosis—this suggests inflammation that could both mask iron deficiency (via elevated ferritin) and impair response to oral iron 1, 2
- Do not perform extensive GI investigation for non-anemic iron deficiency in the absence of other concerning features, as the yield for serious pathology is low 1
- Do not use ferritin alone in the context of inflammation—transferrin saturation and clinical context are essential for accurate interpretation 1