In an adult with ferritin 214 µg/L, serum iron 63 µg/dL, total iron‑binding capacity 306 µg/dL, and transferrin saturation 21 %, what does this iron panel indicate and what are the appropriate next steps?

Iron Panel Interpretation: Borderline Iron-Deficient Erythropoiesis

Your iron panel shows borderline iron-deficient erythropoiesis with transferrin saturation at the lower limit of normal (21%), despite adequate ferritin stores (214 µg/L), requiring investigation for underlying chronic inflammatory conditions or occult blood loss.

Laboratory Interpretation

Your iron parameters reveal:

• Ferritin 214 µg/L is within the normal reference range (20–250 µg/L for men, 20–200 µg/L for women) and indicates adequate total body iron stores 1
• Transferrin saturation 21% sits just above the 20% threshold that defines iron-deficient erythropoiesis, indicating marginal iron availability for red blood cell production 1, 2
• Serum iron 63 µg/dL falls within the normal range (50–175 µg/dL), though this value has limited diagnostic utility due to high day-to-day variability and diurnal fluctuations 1, 2
• TIBC 306 µg/dL is normal (250–370 µg/dL), indicating appropriate transferrin production 1

Clinical Significance

The combination of normal-to-elevated ferritin with borderline-low transferrin saturation raises two important diagnostic possibilities:

1. Early Functional Iron Deficiency

• Functional iron deficiency occurs when ferritin is 100–300 ng/mL with TSAT <20% in the setting of chronic inflammation, where hepcidin traps iron in storage sites making it unavailable for erythropoiesis 2
• Your TSAT of 21% is just above this threshold, suggesting you may be on the borderline of developing functional iron deficiency if an underlying inflammatory condition is present 2
• Ferritin behaves as an acute-phase reactant; inflammation can falsely elevate ferritin levels up to 100–300 µg/L even when true iron deficiency exists 1, 2

2. Occult Chronic Disease or Blood Loss

• In men and postmenopausal women, this pattern mandates gastrointestinal evaluation (endoscopy, colonoscopy) to exclude malignancy as a source of chronic blood loss 2
• Chronic inflammatory conditions—including chronic kidney disease, heart failure, inflammatory bowel disease, and cancer—commonly present with this iron profile 2

Recommended Next Steps

Immediate Laboratory Work-Up

1. Complete blood count (CBC) to assess for anemia (hemoglobin, hematocrit, MCV) and determine if iron-deficient erythropoiesis has progressed to anemia 2
2. C-reactive protein (CRP) to identify chronic inflammation that would explain the ferritin-TSAT discordance 2
3. Renal function tests (creatinine, eGFR) to evaluate for chronic kidney disease, which dramatically increases anemia prevalence when GFR <30 mL/min/1.73 m² 2

Clinical Evaluation

• In men and postmenopausal women: Gastrointestinal investigation is mandatory to exclude occult malignancy 2
• In premenopausal women: Assess menstrual blood loss patterns to identify gynecologic sources of iron loss 2
• All patients: Evaluate for chronic inflammatory conditions (CKD, heart failure, IBD), NSAID use, frequent blood donation, or high-impact athletic activity causing hemolysis 2

Treatment Algorithm

If CRP is Normal (No Inflammation)

• Your iron status is adequate; no treatment is needed at this time 1, 2
• Monitor iron parameters every 6–12 months if risk factors for iron loss persist 2
• Maintain TSAT ≥20% to ensure adequate iron availability for erythropoiesis 1, 2

If CRP is Elevated (Inflammation Present)

• Oral iron (100–200 mg elemental iron daily) is first-line if TSAT remains ≥20% and no severe inflammation is present 2
• Intravenous iron (ferric carboxymaltose, iron sucrose, or low-molecular-weight iron dextran) is preferred if:
  • TSAT drops below 20% on repeat testing 2
  • Chronic kidney disease with eGFR <30 mL/min/1.73 m² 1, 2
  • Heart failure (NYHA class II–III) with ferritin 100–300 ng/mL and TSAT <20% 2
  • Active inflammatory bowel disease 2
  • Gastrointestinal intolerance to oral iron 1, 2
• IV iron bypasses hepcidin-mediated blockade of intestinal iron absorption that occurs in inflammatory states 2

Monitoring After Treatment

• Do not recheck iron parameters within 4 weeks of IV iron infusion because circulating iron interferes with assay accuracy 1, 2
• Optimal re-assessment timing is 4–8 weeks after the last IV iron dose or 8–10 weeks after initiating oral iron 2
• Target TSAT ≥20% after iron repletion to ensure sufficient iron availability for red-cell production 1, 2
• Adequate iron therapy should raise hemoglobin by 1–2 g/dL within 4–8 weeks if anemia is present 2

Common Diagnostic Pitfalls

• Relying on serum iron alone is unreliable due to high intra-individual variability, diurnal fluctuations, and post-prandial changes; normal serum iron does not exclude iron deficiency 2
• Interpreting ferritin without TSAT can miss functional iron deficiency in the setting of inflammation; both must be interpreted together 2
• Failing to investigate underlying causes in men and postmenopausal women can delay diagnosis of gastrointestinal malignancy 2
• Measuring iron parameters too early after IV iron (within 4 weeks) yields falsely elevated results 1, 2