Normal Serum Ferritin Levels in Adults
The normal reference range for serum ferritin is approximately 15–30 ng/mL as the lower limit in most laboratories, with sex-specific ranges of roughly 30–200 ng/mL for women and 30–300 ng/mL for men, though these traditional laboratory ranges substantially underestimate iron deficiency and should not be used as diagnostic thresholds. 1, 2
Sex-Specific Reference Ranges
Women (Non-Pregnant)
- Average ferritin concentration in healthy adult women is approximately 43 ng/mL 1, 3
- Traditional laboratory lower limit of normal: 15–30 ng/mL 1
- Menstruating women typically have median values in the 30s ng/mL range 3
- Women under age 50 years: 3–148 ng/mL (based on Chinese population data) 4
- Women age 50 years and older: 17–304 ng/mL 4
- Historical reference from 1975 reported upper limit of 146 ng/mL (mean 34 ng/mL) 5
Men
- Traditional laboratory lower limit of normal: 25–30 ng/mL 2
- Reference range: 66–572 ng/mL (based on Chinese population data) 4
- Historical reference from 1975 reported upper limit of 193 ng/mL (mean 93 ng/mL) 5
Pregnant Women
The provided evidence does not contain specific ferritin reference ranges for pregnant women, though it is well-established in general medical knowledge that ferritin levels decline during pregnancy due to increased iron demands.
Critical Clinical Thresholds vs. Laboratory "Normal"
A major pitfall exists between laboratory-reported "normal" ranges and clinically meaningful thresholds for iron deficiency:
Iron Deficiency Diagnostic Thresholds
- Ferritin < 30 ng/mL indicates low body iron stores with high sensitivity and specificity for iron deficiency in adults 1
- Ferritin < 15 ng/mL provides 100% specificity for absent bone marrow iron stores in women of childbearing age 1
- Ferritin ≤ 12 ng/mL yields 100% specificity for iron deficiency 3
- Recent multinational evidence suggests physiologically based thresholds should be approximately 25 ng/mL for women and 22 ng/mL for children, substantially higher than WHO guidelines 6
Iron Overload Screening Thresholds
- For hemochromatosis screening: >250 ng/mL in men and >200 ng/mL in women 7
- For C282Y homozygotes in the HEIRS study: >300 ng/mL in men, >200 ng/mL in women 7
- Ferritin >1000 ng/mL with elevated aminotransferases and platelets <200 predicts cirrhosis in 80% of C282Y homozygotes 7
Important Caveats and Pitfalls
Ferritin as an Acute Phase Reactant
- Ferritin is falsely elevated by inflammation, infection, liver disease, malignancy, and tissue injury independent of true iron status 7, 1, 3
- In the presence of inflammation, ferritin < 45 ng/mL still suggests iron deficiency with 92% specificity 1
- Measuring C-reactive protein (CRP) alongside ferritin is recommended when inflammation is suspected 1
- Conditions causing false elevation include chronic hepatitis B/C, alcoholic liver disease, nonalcoholic fatty liver disease, and lymphomas 7
Methodological Quality Issues
- A systematic review found that 49% of studies establishing ferritin reference intervals did not screen for iron deficiency in their "healthy" populations, and 52% did not follow established guidelines 2
- This methodological weakness means traditional laboratory reference ranges likely include iron-deficient individuals, artificially lowering the reported "normal" range 2
Clinical Decision-Making Algorithm
When interpreting ferritin results:
- If ferritin < 30 ng/mL without inflammation → diagnose iron deficiency 1
- If ferritin 30–45 ng/mL with inflammation → likely iron deficiency; check CRP 1
- If ferritin > 200 ng/mL (women) or > 250 ng/mL (men) → consider hemochromatosis screening with transferrin saturation 7
- If ferritin elevated with normal transferrin saturation → investigate inflammatory causes 7
The prevalence of iron deficiency is substantially underestimated when using traditional WHO guidelines (ferritin <15 ng/mL) compared to physiologically based thresholds (ferritin <25 ng/mL), with multinational data showing 36% vs. 20% prevalence in women using these respective cutoffs. 6