Ferritin Blood Test: Normal Levels, Low & High Ferritin

Ferritin is the protein that stores iron, and its blood level is the best single reflection of your iron stores. That makes the ferritin blood test the earliest, most specific way to catch iron deficiency, often long before anemia shows on a blood count. Low ferritin almost always means your reserves are running out; high ferritin, in the vast majority of cases, signals inflammation, not serious disease.

Key takeaways

• Ferritin stores iron; its blood level is proportional to your reserves.¹ Typical U.S. ranges: females ~15–205 ng/mL, males ~30–566 ng/mL, varying by lab, sex, and age.² 1 ng/mL = 1 µg/L — no conversion needed.
• The deficiency threshold is contested. The WHO uses < 15 µg/L in non-pregnant women and < 24 µg/L in men; most U.S. practice uses < 30 ng/mL; the American Gastroenterological Association uses < 45 ng/mL.³⁴⁵
• Iron deficiency is common in the U.S.: about 14% of adults have absolute and 15% functional iron deficiency — much of it without anemia.⁶
• Ferritin is an acute-phase reactant: inflammation, infection, obesity, liver disease, and alcohol push it up and can mask a real deficiency.⁷⁴ So a high ferritin is most often inflammation, fatty liver, or alcohol — rarely hereditary hemochromatosis, and never a cancer marker.⁸ It's never read alone: interpret it with transferrin saturation, CRP, and your context.⁹

What is ferritin?

Iron carries oxygen inside hemoglobin, powers your muscles, and drives dozens of enzymes. But your body cannot efficiently excrete excess iron, so it stores it — mostly in the liver — inside a protein shell called ferritin. A small fraction leaks into the blood in proportion to your stores, so measuring it is essentially reading the fuel gauge on your iron tank.¹ It is the first marker to fall in iron deficiency, dropping before hemoglobin — the most specific test there is.¹⁰⁷

The catch — and the single most important thing about this test — is that ferritin is also an acute-phase reactant. During infection, inflammation, or chronic disease it rises independently of your iron stores, pushing a genuinely deficient person's result into the "normal" range.⁴⁷ That is why ferritin is always read alongside other markers.

Why is ferritin measured?

Your clinician usually orders ferritin as part of an iron panel to investigate signs of low iron (fatigue, hair loss, restless legs syndrome, shortness of breath on exertion), to confirm and monitor iron deficiency or iron-deficiency anemia, to watch at-risk groups (heavy periods, pregnancy, vegan diets, blood donors, endurance athletes), or to work up a high ferritin and screen for iron overload (hemochromatosis).¹²¹¹

Do you need to fast for a ferritin test?

For ferritin alone, fasting is generally not required — its level is stable through the day. But serum iron, drawn with it on an iron panel, varies with meals and time of day, so iron studies are usually collected in the morning; some providers ask for a 12-hour fast.¹ Follow your provider's instructions.

Normal ferritin levels

These indicative U.S. reference values depend on sex, age, and the lab's assay — Cleveland Clinic notes "labs may have different reference ranges," so always compare your number to the range on your report.²

Good to know: the U.S. unit ng/mL and the international µg/L are numerically identical — 1 ng/mL = 1 µg/L — so there is no conversion to do, ever.

A lab "reference range" describes the population that lab tested — not what's healthy. That's why the top of the male range (566 ng/mL) sits far above the WHO's threshold for considering iron overload risk (200 µg/L in men).³ A result inside your lab's range can still be worth a conversation.

Why the low-ferritin threshold is disputed

There is no single agreed cutoff for iron deficiency, and the differences are large enough to change whether you're told you have a problem:

Why the spread? A very low ferritin is highly specific but poorly sensitive. It is still by far the most powerful single test for iron deficiency — area under the ROC curve 0.95 in the classic meta-analysis¹³ — yet under 10–15 ng/mL you're deficient with near-certainty while the test misses many people who are genuinely low. Raising the cutoff to 30 ng/mL improves sensitivity from 25% to 92% while specificity stays at 98%,¹² the basis for the U.S. shift toward 30; a Cochrane review with the WHO likewise found around 30 µg/L both sensitive and highly specific.⁷ The AGA pushes to 45 ng/mL (85% sensitivity, 92% specificity) in patients who already have anemia.⁵

How much does this matter? In a national U.S. study of females aged 12–21, iron deficiency prevalence was 17% at < 15 µg/L, 38.6% at < 25 µg/L, and 77.5% at < 50 µg/L.¹⁴ Same girls, same blood — the threshold alone swings the answer from "uncommon" to "most of them."

What this means for you: a ferritin between roughly 15 and 45 ng/mL with symptoms is a genuine gray zone — "normal" to your lab yet treated as deficient by many clinicians. Worth a conversation, especially since a low-normal ferritin with a high RDW or low MCV points strongly toward real deficiency.

Interpreting your results

Low ferritin: iron deficiency

A low ferritin essentially always means depleted iron stores — the most specific marker available.¹⁰⁷ It can be low long before anemia appears (iron deficiency without anemia): in U.S. females aged 12–21 with iron deficiency, 83.6% did not have iron-deficiency anemia, so a hemoglobin-based screen would have cleared them.¹⁴

Iron deficiency is common in the U.S. In NHANES 2017–2020 data, 14% of adults had absolute iron deficiency (ferritin < 30 ng/mL) and 15% functional iron deficiency (ferritin ≥ 30 ng/mL with transferrin saturation < 20%). Even among adults without anemia, heart failure, kidney disease, or pregnancy, absolute deficiency ran at 11%.⁶

Symptoms — even without anemia — include fatigue, exercise intolerance, shortness of breath on exertion, hair loss, brittle nails, cold intolerance, and restless legs syndrome. For restless legs, guidelines recommend oral iron at ferritin ≤ 75 µg/L and IV iron at < 300 µg/L — far above any "deficiency" cutoff, because the brain's iron needs aren't captured by the standard range.¹⁵

The most common causes:

• Blood loss — heavy menstrual periods (the leading cause in premenopausal women) and gastrointestinal bleeding (ulcers, polyps, colon cancer, NSAIDs).
• Inadequate intake — diets low in bioavailable iron, including vegetarian and vegan patterns.
• Malabsorption — celiac disease, H. pylori, inflammatory bowel disease, and bariatric surgery.
• Increased demand — pregnancy, growth in children and adolescents, and endurance athletes — plus frequent blood donation.

The rule that must never be broken: in an adult man or a postmenopausal woman, iron deficiency requires a search for gastrointestinal bleeding with bidirectional endoscopy, which finds colonic cancer in about 9% and upper GI cancer in about 2% of these patients.¹²⁵ Not a test to postpone.

On your CBC, iron deficiency leaves fingerprints: a low MCV and MCHC, a rising RDW (often the earliest change), and eventually a falling hemoglobin and red blood cell count. It also causes reactive thrombocytosis, so a high platelet count with a low ferritin is a recognized pairing.

Treatment is your doctor's call, with two halves: replace the iron (oral first, IV when oral fails) and find out why it was lost — supplementing without answering the second can mask a bleeding lesion for months.¹⁰

High ferritin: causes and when to worry

A high ferritin frightens people, but it is rarely serious. The common causes are benign, reversible, or manageable:⁸⁷

• Inflammation or infection — ferritin rises alongside CRP; by far the most frequent explanation.
• Metabolic syndrome and fatty liver disease (MASLD) — obesity, insulin resistance, and type 2 diabetes, often with a raised ALT.
• Alcohol use — a direct, often-overlooked driver.
• Liver disease — hepatitis, cirrhosis, injury of any cause; and chronic kidney disease.
• Hereditary hemochromatosis — genuine iron overload, the one cause you must not miss (below).
• Rarely, hemophagocytic lymphohistiocytosis (HLH), in which ferritin runs into the thousands in an acutely ill patient.⁸

"Does high ferritin mean cancer?" No — not for a modest elevation. Ferritin reflects inflammation, the liver, and iron — it is not a cancer screening test. Only a very high and unexplained ferritin prompts a broad work-up that includes malignancy.⁸ For a result slightly above range, check CRP, transferrin saturation, alcohol, metabolic markers, and liver enzymes — don't assume the worst.

When should you worry? Not the number alone, but how high it is, the transferrin saturation, the CRP, and the trend. A modest rise with a high CRP means inflammation — recheck once it settles; a markedly or persistently elevated ferritin, especially with a high transferrin saturation, deserves proper evaluation, without panic.

Hereditary hemochromatosis: the genetic cause

Hereditary hemochromatosis is the high-ferritin cause that matters most in the U.S. — both common in Northern European ancestry and highly treatable when caught before organ damage.

About 1 in 15 people of Northern European ancestry carry at least one copy of the HFE C282Y mutation, and roughly 1 in 225 carry two copies, putting them at risk of iron overload.¹⁶ An American Society of Hematology review puts C282Y homozygosity at nearly 1 in 200 people of Northern European descent.¹¹ It is much less common in people of Asian or African ancestry.¹⁶

The body absorbs too much iron and deposits it in the liver, heart, pancreas, endocrine glands, and joints. Symptoms — fatigue, joint pain, loss of libido, and skin darkening — typically emerge after age 40, and about 10 years later in women (menstruation protects until menopause).¹⁶

The key point: ferritin alone cannot make this diagnosis. The diagnostic hallmark is a raised transferrin saturation; HFE genetic testing confirms it.¹¹ A high ferritin with a normal saturation points toward inflammation or fatty liver; with a high saturation, toward iron overload. Treatment is straightforward: therapeutic phlebotomy until iron stores normalize.¹⁶¹¹

Ferritin, serum iron, and transferrin saturation

No one interprets ferritin alone. The iron panel adds serum iron (what's currently circulating, highly variable), transferrin and total iron-binding capacity (TIBC) (the transport protein, rising when iron is scarce), and transferrin saturation (TSAT) — low (< 20%) in deficiency, high in overload, the marker that separates the two directions when ferritin is ambiguous.⁴ CRP distinguishes a truly normal ferritin from an inflammation-inflated one.

When to see a doctor

Contact your clinician if your ferritin is outside your lab's range, or low-normal (roughly 15–45 ng/mL) with symptoms. A low ferritin should prompt a search for the cause — in men and postmenopausal women, evaluate for gastrointestinal bleeding.¹² A high ferritin should be checked against CRP and transferrin saturation; with a high saturation, test for hemochromatosis.¹¹ Seek prompt care for heavy bleeding, black or bloody stools, chest pain, fainting, or severe shortness of breath.

Recent research

According to PubMed and clinical-trial registries:

• The deficiency threshold is being renegotiated. A Cochrane review with the WHO confirms a threshold around 30 µg/L is both sensitive and highly specific in adults, and must be raised when inflammation is present.⁷ National U.S. data show why this matters: prevalence in young females moves from 17% to 77.5% depending on whether the line is 15 or 50 µg/L.¹⁴ (Weyand AC et al., JAMA, 2023 — DOI.)
• Iron deficiency is more common — and more invisible — than assumed. A 2024 NHANES analysis found 14% of U.S. adults with absolute and 15% with functional iron deficiency, most of it without anemia; supplement use among the deficient was low (12–35%).⁶ (Tawfik YMK et al., JAMA Network Open, 2024 — DOI.)
• Ferritin is unreliable in chronic inflammation. In heart failure and kidney disease it overestimates iron stores; transferrin saturation < 20% identifies functional deficiency far better.¹⁷ Major IV iron trials in heart failure — such as AFFIRM-AHF — define deficiency by combining ferritin with saturation for this reason.¹⁸ (Packer M et al., Circulation, 2024 — DOI.)
• Hyperferritinemia calls for a stepwise work-up — transferrin saturation, liver panel, alcohol history, metabolic assessment, and HFE genetic testing when saturation is high — rather than repeating an isolated ferritin.¹⁹⁸ In hemochromatosis, ASH emphasizes that transferrin saturation, not ferritin, is the diagnostic hallmark, with phlebotomy the mainstay.¹¹ (Girelli D et al., Hematology ASH Education Program, 2024 — DOI.)

These findings concern diagnosis and management; they do not authorize self-medication and do not replace your physician's advice.

Get your ferritin interpreted by AI DiagMe

Ferritin is never read alone: its meaning depends on your transferrin saturation, your CRP, your alcohol intake, your liver, your weight, and how the number has moved over time — because the very same ferritin can mean depleted iron in one person and inflammation in another. That cross-referencing is what gives the number its real value.

👉 AI DiagMe interprets your lab results — blood, urine, or stool — in plain language, taking your whole profile into account. An informational service that does not provide a diagnosis and complements, never replaces, your physician.

Frequently asked questions

Bottom line

Ferritin is the gauge of your iron stores — females ~15–205 ng/mL, males ~30–566 ng/mL, varying by lab. Low ferritin means iron deficiency that must be explained, not just supplemented; high ferritin is usually inflammation, fatty liver, or alcohol — not cancer. The "low" threshold is genuinely debated (15 vs 30 vs 45 ng/mL), so a low-normal result with symptoms deserves a conversation. Because ferritin is also an inflammation protein, it is never read alone: its meaning comes from transferrin saturation, CRP, your CBC, and your profile — exactly what AI DiagMe provides, alongside your physician.

Sources

Official sources and peer-reviewed publications (PubMed, ClinicalTrials.gov) used for this guide: