Skip to main content

Longevity Library · Lab reference

Written by Daniel Tagge, MD
Updated October 7, 2026
Reviewed October 10, 2026
21 sources · Measured in ng/mL

System: Mitochondria & Cellular Energy

FerritinSerum ferritin · Iron stores

The evidence places iron deficiency below about 30 ng/mL, shows symptoms respond to iron up to about 50 (75 in restless legs, 100 in heart failure), and links values above about 150 to 200 with higher diabetes and mortality risk in cohorts. Between 50 and 150 the outcome literature is largely silent, so no study defines an optimal ferritin.

Ferritin reflects stored iron, and it rises with inflammation whether or not iron is present. Laboratories call a span from about 15 or 30 up to 150 to 400 ng/mL normal. The literature is firm at the low end, where deficiency and symptoms live, and cautionary at the high end, and says little about the middle.

01 · The scale

Where the laboratory range and the evidence sit.

Firm at the bottom, cautious at the top, quiet in the middle: deficiency below about 30, symptom benefit from iron up to about 50 to 100 depending on the condition, higher diabetes and mortality risk above about 150 to 200.

050100150200300400

  1. Common laboratory reference range (women)

    15 to 150 ng/mL · Typical US laboratories

  2. Common laboratory reference range (men)

    30 and above ng/mL · Typical US laboratories

  3. Iron deficiency

    0 to 30 ng/mL · WHO 2020; Mast 1998

  4. Fatigue in women improved with iron below 50

    30 to 50 ng/mL · Vaucher 2012

  5. Restless legs: oral iron possibly effective up to 75

    50 to 75 ng/mL · IRLSSG 2018

  6. No outcome signal either way

    75 to 150 ng/mL · No cohort or trial addresses this span in healthy adults

  7. Higher diabetes and mortality risk in cohorts

    150 and above ng/mL · Sun 2024; Ellervik 2014; Jiang 2004

  • Laboratory range
  • Evidence supports
  • Guideline goal or unstudied
  • Higher risk in studies
Scale in ng/mL. ng/mL is the same as µg/L. Bands show where studies found something, not a recommendation for any one person.

02 · What it is

What Ferritin measures.

Ferritin is the protein that stores iron inside cells; the small amount in blood tracks total body iron stores closely enough that it is the single best blood test for iron deficiency, with an area under the curve of 0.95 against bone-marrow iron.1Grade A

Iron stores run down before hemoglobin falls. Absolute iron deficiency, defined by low stores with or without anemia, affects about 14 percent of US adults, and among adults without anemia, heart failure, kidney disease or pregnancy it still affects about 11 percent. Fatigue, poor concentration, restless legs, exercise intolerance and hair loss can appear at this stage.2,3Grade A

Ferritin is also an acute-phase reactant. Infection, inflammation, fatty liver, alcohol and obesity raise it independently of iron, which is why a reassuring or alarming ferritin must be read next to a marker of inflammation such as C-reactive protein and next to transferrin saturation.4,5Grade A

03 · The laboratory range

What a laboratory calls normal.

About 15 to 150 ng/mL for women and 30 to 400 ng/mL for men, depending on the laboratory.

The lower limit most laboratories print, 12 to 15 ng/mL, is specific for iron deficiency but misses most cases: in patients confirmed by bone marrow or by response to iron, a cutoff of 12 found only 25 percent, while a cutoff of 30 found 92 percent and still kept specificity at 98 percent.6Grade B

The World Health Organization's 2020 guideline sets ferritin below 15 ng/mL as iron deficiency in apparently healthy adults, below 70 in adults with infection or inflammation, and flags possible iron overload above 150 in menstruating women, above 200 in men and non-menstruating women, and above 500 in people with inflammation. The guideline rates its own evidence as low certainty and asks for inflammation to be assessed alongside.4Grade A

04 · The evidence

What the studies support.

In 198 menstruating women with unexplained fatigue, a hemoglobin of 12 g/dL or more and a ferritin below 50 ng/mL, 12 weeks of oral iron cut the fatigue score by 48 percent against 29 percent on placebo. A separate trial of intravenous iron in women with ferritin of 50 or less found the benefit concentrated in those starting at 15 or below.7,8Grade B

Pooling 18 randomized trials of iron in non-anemic iron-deficient adults, iron reduced self-reported fatigue (standardized mean difference -0.38, no heterogeneity across four trials) but did not change objective exercise capacity such as maximal oxygen uptake. In endurance athletes specifically, iron treatment did raise maximal oxygen uptake.9,10Grade A

Condition-specific thresholds sit higher than the deficiency cutoff. The international restless legs guideline rates oral iron as possibly effective when ferritin is 75 or below and intravenous iron as effective below 300. In chronic heart failure, treating a ferritin below 100 (or 100 to 299 with transferrin saturation under 20 percent) with intravenous iron improved symptoms and walking distance in a randomized trial, whether or not anemia was present.11,12Grade A

At the high end, in 29,166 US adults followed for a median of 19 years, the top quartile of ferritin (above 157 ng/mL) had 13 percent higher all-cause mortality than the bottom quartile (below 35); among people without diabetes it carried 19 percent higher cardiovascular and 25 percent higher cancer mortality. The population median was 77. An association in a cohort, adjusted for the usual confounders, not proof that ferritin causes the deaths.13Grade B

In the Copenhagen general population, ferritin of 200 or more carried a 10 percent higher adjusted mortality, rising stepwise: median survival was 79 years below 200, 76 at 200 to 399, 72 at 400 to 599 and 55 at 600 or above. A meta-analysis of other cohorts in the same paper found no excess in the upper quartile overall, so the signal is clearest at markedly raised values.14Grade B

Higher iron stores predict type 2 diabetes. In the Nurses' Health Study the highest quintile of ferritin carried 2.7 times the risk of the lowest, independent of body weight and C-reactive protein; in EPIC-Norfolk, clinically raised ferritin carried 7.4 times the odds, falling to 3.2 after adjusting for liver enzymes, which suggests fatty liver explains part of it. A meta-analysis of 11 prospective studies put the pooled risk at 1.6 to 1.7 for the highest versus lowest ferritin. Genetic studies suggest higher ferritin may itself drive low-grade inflammation.15,16,17,18Grade B

A ferritin above 300 ng/mL in men or above 200 in women with a transferrin saturation of 45 percent or more is the gastroenterology guideline's trigger to test for hereditary hemochromatosis. The same guideline notes that fatty liver and alcohol are more common causes of a raised ferritin than hemochromatosis.5Grade A

05 · What moves it

The levers with evidence behind them.

What is listed here has been tested. The size of each effect, and the size of the study, are in the sentence, so a small effect reads as a small effect.

  • Oral iron, taken every other day

    raises it, with better absorption on alternate days

    In iron-depleted women, the same total dose of oral iron given on alternate days was absorbed better than consecutive daily doses, because a daily dose raises hepcidin and blocks the next day's absorption. Iron supplements belong under a physician's direction once the cause of deficiency is known.19Grade B

  • Blood donation

    lowers it

    In the REDS-II study of US blood donors, iron depletion was common and rose with donation frequency; a ferritin draw is worth repeating after a run of donations before reading a low value as a disease.20Grade B

  • Heme iron from red meat

    raises stores; higher intake tracks with diabetes

    Across prospective studies, the highest heme-iron intake carried a 33 percent higher risk of type 2 diabetes, 16 percent per additional milligram a day; total, non-heme and supplemental iron intake showed no association.17Grade B

  • Inflammation, fatty liver and alcohol

    raise it without adding iron

    Because ferritin is an acute-phase protein, infection, inflammation, fatty liver and alcohol raise it independently of iron stores. In the WHO guideline the deficiency threshold more than quadruples, from 15 to 70 ng/mL, when inflammation is present.4,5Grade A

06 · Reading it well

Caveats, and what belongs with a physician.

Read ferritin with transferrin saturation and C-reactive protein. A normal ferritin with a low transferrin saturation can still be functional iron deficiency, which affects about 15 percent of US adults; a high ferritin with a normal saturation usually points to inflammation or liver fat rather than iron overload.2,5Grade A

A low ferritin in a man or a postmenopausal woman is a finding to explain, not only to treat: gastroenterology guidelines call for evaluation of the digestive tract for a source of blood loss.21Grade A

The benefit of iron for fatigue is modest and shows up in self-report, not in measured exercise capacity, in the pooled trials of non-anemic adults; the clearest benefit is in people with the lowest stores.9,8Grade A

See a physician

  • A ferritin below 30 ng/mL in a man, or in a woman after menopause, which needs a search for blood loss before any iron is taken.
  • Black or bloody stools, heavy periods, or unexplained weight loss alongside a low ferritin.
  • A ferritin above 300 (men) or 200 (women) with a transferrin saturation of 45 percent or more, or any ferritin above 1,000.
  • Shortness of breath, chest pain, or a rapid heartbeat with a low ferritin or anemia.

This page is education, not individual medical advice, and reading it creates no physician-patient relationship.

07 · Open questions

What the literature does not settle.

  • No trial has treated healthy adults to a ferritin target between 50 and 150 ng/mL and measured outcomes; an optimal zone inside that span is a clinical judgment, not a finding.
  • The mortality and diabetes associations above about 150 to 200 come from cohorts and may partly reflect fatty liver and inflammation rather than iron itself; Mendelian randomization points both ways.
  • Whether treating non-anemic iron deficiency improves hair loss, cognition or mood is unsettled; the trials are small and mixed.
  • Sex- and age-specific optimal ranges have not been established; most low-end trials enrolled menstruating women.

08 · In practice

How Dr. Tagge reads it in his own practice.

I like to see ferritin between about 80 and 150 in women and about 80 and 200 in men, read beside transferrin saturation and C-reactive protein. That window is my judgment: it sits above every threshold at which iron has relieved symptoms in a trial and below the levels that keep company with higher risk in the cohorts, and the two ceilings line up with the WHO overload thresholds for each sex. In a man or a postmenopausal woman, a low ferritin is a question about blood loss before it is a prescription.

A practice judgment, labeled as one (Grade D): it is how one physician reads the number for the people he cares for, not a recommendation for you.

09

Questions

10 · Sources

21 sources, read in full.

Numbered in the order they appear. Each line says what this page relies on from the paper; the link opens the record at PubMed or the publisher.

  1. 1.

    Guyatt GH, Oxman AD, Ali M, Willan A, McIlroy W, Patterson C. Laboratory diagnosis of iron-deficiency anemia: an overview. Journal of General Internal Medicine. 1992. PMID 1487761. DOI 10.1007/BF02598003.

    Systematic review and meta-analysis · Serum ferritin was the most powerful test for iron-deficiency anemia, area under the curve 0.95.

  2. 2.

    Tawfik YMK, Billingsley H, Bhatt AS, et al.. Absolute and functional iron deficiency in the US, 2017-2020. JAMA Network Open. 2024. PMID 39316402. DOI 10.1001/jamanetworkopen.2024.33126.

    Cross-sectional study · 14 percent of US adults had absolute iron deficiency and 15 percent functional iron deficiency; 11 percent absolute among those without anemia or major illness.

  3. 3.

    Auerbach M, DeLoughery TG, Tirnauer JS. Iron deficiency in adults: a review. JAMA. 2025. PMID 40159291. DOI 10.1001/jama.2025.0452.

    Review · Non-anemic iron deficiency can cause fatigue, poor concentration, restless legs and exercise intolerance; bleeding and malabsorption are the usual causes.

  4. 4.

    World Health Organization. WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations. World Health Organization, Geneva. 2020.

    Guideline · Deficiency below 15 µg/L in healthy adults, below 70 with inflammation; overload risk above 150 (menstruating women), 200 (men, non-menstruating women), 500 (with inflammation).

  5. 5.

    Kowdley KV, Brown KE, Ahn J, Sundaram V. ACG clinical guideline: hereditary hemochromatosis. American Journal of Gastroenterology. 2019. PMID 31335359. DOI 10.14309/ajg.0000000000000315.

    Guideline · Ferritin above 300 (men) or 200 (women) with transferrin saturation 45 percent or more prompts HFE testing; fatty liver and alcohol raise ferritin more often than hemochromatosis.

  6. 6.

    Mast AE, Blinder MA, Gronowski AM, Chumley C, Scott MG. Clinical utility of the soluble transferrin receptor and comparison with serum ferritin in several populations. Clinical Chemistry. 1998. PMID 9550557.

    Cross-sectional study · A ferritin cutoff of 30 µg/L had 92 percent sensitivity and 98 percent specificity for iron deficiency, against 25 percent sensitivity at 12.

  7. 7.

    Vaucher P, Druais PL, Waldvogel S, Favrat B. Effect of iron supplementation on fatigue in nonanemic menstruating women with low ferritin: a randomized controlled trial. CMAJ. 2012. PMID 22777991. DOI 10.1503/cmaj.110950.

    Randomized trial · Oral iron for 12 weeks reduced fatigue 47.7 percent versus 28.8 percent on placebo in women with ferritin below 50 µg/L.

  8. 8.

    Krayenbuehl PA, Battegay E, Breymann C, Furrer J, Schulthess G. Intravenous iron for the treatment of fatigue in nonanemic, premenopausal women with low serum ferritin concentration. Blood. 2011. PMID 21705493. DOI 10.1182/blood-2011-04-346304.

    Randomized trial · Benefit of intravenous iron on fatigue was confined to women with baseline ferritin of 15 ng/mL or less.

  9. 9.

    Houston BL, Hurrie D, Graham J, et al.. Efficacy of iron supplementation on fatigue and physical capacity in non-anaemic iron-deficient adults: a systematic review of randomised controlled trials. BMJ Open. 2018. PMID 29626044. DOI 10.1136/bmjopen-2017-019240.

    Systematic review and meta-analysis · Iron reduced self-reported fatigue (SMD -0.38) but not maximal oxygen uptake in 18 trials of non-anemic iron-deficient adults.

  10. 10.

    Burden RJ, Morton K, Richards T, Whyte GP, Pedlar CR. Is iron treatment beneficial in iron-deficient but non-anaemic endurance athletes? A systematic review and meta-analysis. British Journal of Sports Medicine. 2015. PMID 25361786. DOI 10.1136/bjsports-2014-093624.

    Systematic review and meta-analysis · Iron treatment improved iron status and maximal oxygen uptake in iron-deficient non-anemic endurance athletes.

  11. 11.

    Allen RP, Picchietti DL, Auerbach M, et al.. Evidence-based and consensus clinical practice guidelines for the iron treatment of restless legs syndrome/Willis-Ekbom disease in adults and children: an IRLSSG task force report. Sleep Medicine. 2018. PMID 29425576. DOI 10.1016/j.sleep.2017.11.1126.

    Guideline · Oral iron possibly effective for restless legs at ferritin 75 µg/L or below; intravenous ferric carboxymaltose effective below 300.

  12. 12.

    Anker SD, Comin Colet J, Filippatos G, et al.. Ferric carboxymaltose in patients with heart failure and iron deficiency. New England Journal of Medicine. 2009. PMID 19920054. DOI 10.1056/NEJMoa0908355.

    Randomized trial · In heart failure with ferritin below 100, or 100 to 299 with transferrin saturation under 20 percent, intravenous iron improved symptoms and walking distance with or without anemia.

  13. 13.

    Sun Y, Peng W, Lin S, Cui J, Lu J. Iron metabolic biomarkers and the mortality risk in the general population: a nationwide population-based cohort study. Journal of the Endocrine Society. 2024. PMID 38623382. DOI 10.1210/jendso/bvae063.

    Prospective cohort · Top ferritin quartile (above 157 ng/mL) had 13 percent higher all-cause mortality than the bottom quartile (below 35) over a median 19 years in NHANES; median ferritin 77.

  14. 14.

    Ellervik C, Marott JL, Tybjærg-Hansen A, Schnohr P, Nordestgaard BG. Total and cause-specific mortality by moderately and markedly increased ferritin concentrations: general population study and metaanalysis. Clinical Chemistry. 2014. PMID 25156997. DOI 10.1373/clinchem.2014.229013.

    Prospective cohort · Ferritin 200 µg/L or more carried 1.1 times the mortality; 600 or more, 1.5 times; stepwise fall in median survival.

  15. 15.

    Jiang R, Manson JE, Meigs JB, Ma J, Rifai N, Hu FB. Body iron stores in relation to risk of type 2 diabetes in apparently healthy women. JAMA. 2004. PMID 14871914. DOI 10.1001/jama.291.6.711.

    Prospective cohort · Highest ferritin quintile carried 2.68 times the risk of type 2 diabetes in women, independent of BMI and C-reactive protein.

  16. 16.

    Forouhi NG, Harding AH, Allison M, et al.. Elevated serum ferritin levels predict new-onset type 2 diabetes: results from the EPIC-Norfolk prospective study. Diabetologia. 2007. PMID 17333112. DOI 10.1007/s00125-007-0604-5.

    Prospective cohort · Clinically raised ferritin carried 7.4 times the odds of diabetes, 3.2 after adjustment for liver enzymes and adiponectin.

  17. 17.

    Bao W, Rong Y, Rong S, Liu L. Dietary iron intake, body iron stores, and the risk of type 2 diabetes: a systematic review and meta-analysis. BMC Medicine. 2012. PMID 23046549. DOI 10.1186/1741-7015-10-119.

    Systematic review and meta-analysis · Highest versus lowest ferritin: pooled relative risk of type 2 diabetes 1.63 after inflammation adjustment; heme iron intake 1.33.

  18. 18.

    Moen IW, Bergholdt HKM, Mandrup-Poulsen T, Nordestgaard BG, Ellervik C. Increased plasma ferritin concentration and low-grade inflammation: a Mendelian randomization study. Clinical Chemistry. 2018. PMID 29038157. DOI 10.1373/clinchem.2017.276055.

    Mendelian randomization · Genetically higher ferritin was associated with higher C-reactive protein, suggesting ferritin may drive low-grade inflammation.

  19. 19.

    Stoffel NU, Zeder C, Brittenham GM, Moretti D, Zimmermann MB. Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica. 2020. PMID 31413088. DOI 10.3324/haematol.2019.220830.

    Randomized trial · Alternate-day oral iron was absorbed better than consecutive-day dosing because daily dosing raises hepcidin.

  20. 20.

    Cable RG, Glynn SA, Kiss JE, et al.. Iron deficiency in blood donors: the REDS-II Donor Iron Status Evaluation (RISE) study. Transfusion. 2012. PMID 22023513. DOI 10.1111/j.1537-2995.2011.03401.x.

    Prospective cohort · Iron depletion was common in US blood donors and increased with donation frequency.

  21. 21.

    Ko CW, Siddique SM, Patel A, et al.. AGA clinical practice guidelines on the gastrointestinal evaluation of iron deficiency anemia. Gastroenterology. 2020. PMID 32810434. DOI 10.1053/j.gastro.2020.06.046.

    Guideline · Iron deficiency in men and postmenopausal women warrants bidirectional endoscopy to find a source of blood loss.

Related

Keep reading.

Reading a number well is the start of the work, not the end of it. If you would like a physician to read yours over time, Explore working with Dr. Tagge.