What is the normal ferritin (iron storage protein) reference range for adults?

Ferritin Reference Range

The normal ferritin reference range for adults is 20-250 μg/L in men and 20-200 μg/L in women, according to the 2022 ESPEN micronutrient guideline. 1

Standard Reference Intervals by Sex

• Men: 20-250 μg/L (with some sources reporting 24-336 μg/L) 1
• Women: 20-200 μg/L (with some sources reporting 11-307 μg/L) 1

The ESPEN guideline provides the most clinically relevant thresholds, though there is some variation in the literature due to different immunological assay methods used to measure serum ferritin. 1

Critical Clinical Thresholds for Interpretation

Iron Deficiency Thresholds

• Ferritin <15 μg/L: Has 99% specificity for absolute iron deficiency and definitively confirms the diagnosis 1, 2
• Ferritin <30 μg/L: Generally indicates depleted body iron stores and warrants treatment consideration 1, 2
• Ferritin <45 μg/L: Provides optimal sensitivity-specificity balance (92% specificity) for clinical decision-making and may justify gastrointestinal investigation 1, 2

Iron Overload Thresholds

• Ferritin >150 μg/L: Rarely occurs with absolute iron deficiency, even in the presence of inflammation 1
• Ferritin >500 μg/L: Suggests adequate or excessive iron stores in non-dialysis patients 3
• Ferritin >800 μg/L: Substantially increases iron overload risk 3

Essential Caveat: The Inflammation Problem

Ferritin is an acute-phase reactant that rises during inflammation, infection, liver disease, and malignancy, potentially masking true iron deficiency. 1, 2, 3 This is the single most important pitfall in ferritin interpretation.

Adjusted Thresholds in Inflammatory Conditions

• In patients with inflammatory bowel disease, chronic kidney disease, heart failure, or other chronic inflammatory conditions, the threshold for iron deficiency shifts upward to ferritin <100 μg/L 2, 3
• Ferritin levels may be falsely normal or elevated despite depleted iron stores when inflammation coexists 1
• Always check inflammatory markers (CRP, ESR) when ferritin results seem discordant with clinical presentation 2

Complementary Testing Required

Ferritin should never be interpreted in isolation. 1, 2 The following parameters must be assessed simultaneously:

• Transferrin saturation (TSAT): Values <16-20% indicate iron deficiency even with higher ferritin levels 1, 2
• Hemoglobin: To distinguish iron deficiency with anemia from iron deficiency without anemia 1
• Inflammatory markers (CRP/ESR): To determine if ferritin is falsely elevated 1, 2

Methodological Limitations

• Variability in immunological assay methods means no universally agreed generic reference ranges exist 1
• Laboratories should indicate their own reference ranges when using commercial methods 1
• Recent systematic review evidence reveals that published ferritin reference intervals are at high risk of bias, as many studies failed to exclude individuals at risk for iron deficiency from their "normal" population samples 4
• The literature consistently reports lower limits of normal below 30 μg/L, with median values of 8 μg/L in females and 25 μg/L in males 4

Population-Specific Considerations

• Children (6-24 months): Approximately 30 μg/L according to CDC recommendations 2
• Pregnant women: Lower thresholds apply due to increased iron demands 2
• Chronic kidney disease patients on dialysis: Target range of 50-100 μg/L, with minimum threshold ≥100 μg/L during erythropoietin therapy 3

Clinical Decision Algorithm

When evaluating ferritin results:

1. If ferritin <15 μg/L: Absolute iron deficiency confirmed—initiate treatment and investigate source of iron loss 1, 2
2. If ferritin 15-30 μg/L: Iron deficiency with low stores likely—consider iron supplementation 1, 2
3. If ferritin 30-100 μg/L with elevated CRP/ESR: Mixed picture of iron deficiency and inflammation—address underlying inflammatory condition while treating iron deficiency 1, 2
4. If ferritin >100 μg/L with elevated CRP/ESR: Anemia of chronic disease (inflammatory iron block) likely—treat underlying inflammatory condition as primary intervention 2
5. If ferritin >150 μg/L: Iron deficiency unlikely unless severe inflammation present 1