What ferritin level should be achieved and maintained in a patient with confirmed iron deficiency?

Target Ferritin Levels in Iron Deficiency

For most patients with confirmed iron deficiency, the target ferritin level to achieve and maintain is ≥50 ng/mL, which represents the body's physiologic threshold for adequate iron stores, though specific populations require higher targets.

General Population Target

• The primary goal is ferritin ≥50 ng/mL, as this represents the physiologic threshold below which functional iron deficiency and symptoms commonly occur 1
• This 50 ng/mL target applies regardless of sex and provides optimal balance between detecting true deficiency while maintaining adequate iron stores 1
• Treatment should continue until ferritin normalizes to at least this level 2

Key rationale: The 50 ng/mL threshold achieves 85% sensitivity for detecting iron deficiency while maintaining 92% specificity, and is explicitly recognized as the body's physiologic cutoff for adequate stores 1. Using lower thresholds (like 15 ng/mL) misses nearly 40% of iron-deficient patients 1.

Chronic Kidney Disease (CKD) Patients - Higher Targets Required

Non-Dialysis and Peritoneal Dialysis CKD Patients

• Target ferritin ≥100 ng/mL with transferrin saturation (TSAT) ≥20% 3, 2
• These targets should be maintained to achieve and sustain hemoglobin levels of 11-12 g/dL 3

Hemodialysis Patients - Even Higher Targets

• Target ferritin >200 ng/mL with TSAT >20% for optimal erythropoiesis and reduced erythropoiesis-stimulating agent (ESA) requirements 3, 2
• Randomized trials demonstrate that hemodialysis patients with ferritin targets of 200-400 ng/mL require 28% lower ESA doses compared to lower ferritin targets 3
• Higher transferrin saturation targets (30-50% vs 20-30%) allow hemoglobin maintenance at lower ESA doses 3

Important caveat: Patients are unlikely to benefit from further iron supplementation once TSAT reaches ≥50% or ferritin reaches ≥800 ng/mL 3. Avoid intravenous iron in patients with ferritin >800 ng/mL unless TSAT is <25% and benefits clearly outweigh risks 2.

Monitoring Strategy After Iron Repletion

• Check ferritin and TSAT 4-8 weeks after completing oral iron therapy or after the last iron infusion, as circulating iron interferes with assays if evaluated sooner 1
• Hemoglobin should increase by 1-2 g/dL within 4-8 weeks, indicating successful repletion 1
• Do not evaluate iron parameters within 4 weeks of total dose intravenous iron 1

Special Considerations in Inflammatory States

Critical pitfall: Ferritin is an acute-phase reactant that becomes falsely elevated during inflammation, infection, or malignancy, potentially masking true iron deficiency 1, 4, 5.

When inflammation is present:

• TSAT <20% is more reliable than ferritin for identifying ongoing iron deficiency when results are discordant (elevated ferritin with low TSAT) 1, 4
• Consider soluble transferrin receptor (sTfR) or reticulocyte hemoglobin content, which are not affected by inflammation 1
• In inflammatory conditions (heart failure, CKD, IBD), ferritin <100 ng/mL OR TSAT <20% indicates iron deficiency 4
• If ferritin is 100-300 ng/mL in inflammatory states, TSAT <20% is required to confirm deficiency 4

Ongoing Maintenance

• Frequency of monitoring depends on the underlying cause: patients with ongoing blood loss or malabsorption require more frequent monitoring and repeated iron administration 1
• If the cause of iron deficiency has been eliminated, a single course of iron repletion should suffice 1
• Patients with repeatedly low ferritin benefit from intermittent oral supplementation every 6-12 months to preserve iron stores 6

Avoid this pitfall: Long-term daily oral or intravenous iron supplementation when ferritin is normal or elevated is not recommended and potentially harmful 6. Once ferritin normalizes, discontinue routine supplementation unless ongoing losses persist 2.