Ferritin Blood Test: Normal Levels, Low & High Ferritin

Ferritin is the protein that stores iron in your body, and its level in your blood is the best single reflection of your iron stores. That makes the ferritin blood test the earliest and most specific way to catch iron deficiency — often long before anemia shows up on a complete blood count. Low ferritin almost always means your iron reserves are running out; high ferritin, in the vast majority of cases, signals inflammation rather than a serious disease. This guide explains normal ferritin levels by sex and age, what causes low and high ferritin, why the deficiency threshold is genuinely disputed among experts, whether you need to fast, and when a result is worth raising with your doctor.

Key takeaways

• Ferritin stores iron; the amount circulating in your blood is proportional to your reserves.¹
• Typical U.S. lab ranges: females ~15–205 ng/mL, males ~30–566 ng/mL — but ranges vary by lab, sex, and age.²
• The deficiency threshold is contested. The WHO uses < 15 µg/L in non-pregnant women and < 24 µg/L in men; most U.S. clinical practice uses < 30 ng/mL; the American Gastroenterological Association uses < 45 ng/mL.³⁴⁵ We explain this divergence below rather than pretend there's one number.
• 1 ng/mL = 1 µg/L. The U.S. unit and the international unit are numerically identical, so no conversion is ever needed.
• Iron deficiency is common in the U.S.: about 14% of adults have absolute iron deficiency and 15% have functional iron deficiency — much of it without anemia.⁶
• Ferritin is an acute-phase reactant: inflammation, infection, obesity, liver disease, and alcohol all push it up, which can mask a real iron deficiency.⁷⁴
• High ferritin is most often inflammation, metabolic syndrome/fatty liver, or alcohol — and only rarely hereditary hemochromatosis. It is not a cancer marker.⁸
• Ferritin is never read alone: it's interpreted with transferrin saturation, CRP, and your context.⁹

What is ferritin?

Iron is essential: it carries oxygen inside hemoglobin, powers your muscles, and drives dozens of enzymes. But your body has no efficient way to get rid of excess iron, so it stores it — mostly in the liver — inside a protein shell called ferritin. A small fraction of that ferritin leaks into the bloodstream in proportion to your stores, which means measuring it is essentially reading the fuel gauge on your iron tank.¹

That's what makes the ferritin test so valuable: it is the first marker to fall in iron deficiency, dropping before hemoglobin does and before anemia is diagnosable. Ferritin is the most specific test for iron deficiency there is.¹⁰⁷

But ferritin has a catch, and it's the single most important thing to understand about this test: it is also an acute-phase reactant — an inflammation protein. During infection, inflammation, or chronic disease, ferritin rises independently of your iron stores, which can push 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 may order a ferritin test — usually as part of an iron panel (also called iron studies) — to:¹²

• investigate fatigue, pale skin, hair loss, restless legs syndrome, brittle nails, or shortness of breath on exertion — all possible signs of low iron;
• confirm and monitor iron deficiency or iron-deficiency anemia;
• watch at-risk situations: heavy menstrual periods, pregnancy, vegetarian or vegan diets, frequent blood donation, endurance sports, bariatric surgery, or digestive disease;
• work up a high ferritin found on routine labs, or screen for iron overload (hemochromatosis).¹¹

Do you need to fast for a ferritin test?

For ferritin alone, fasting is generally not required: its concentration is stable through the day. However, serum iron — usually drawn at the same time as part of the iron panel — varies significantly with meals and time of day, which is why iron studies are typically collected in the morning. Some providers do ask for a 12-hour fast before the test.¹ Follow whatever instruction your provider or lab gives you, since consistency matters more than the rule itself when you're tracking results over time.

Normal ferritin levels

Below are indicative reference values for the U.S. They depend on sex, age, and the laboratory's assay — Cleveland Clinic notes explicitly that "labs may have different reference ranges for normal ferritin levels," so always compare your number to the range printed on your report.²

Good to know: ferritin is reported in ng/mL (nanograms per milliliter) in the U.S. and in µg/L (micrograms per liter) internationally. These are numerically identical — 1 ng/mL = 1 µg/L — so a ferritin of 22 ng/mL and 22 µg/L are the same result. There is no conversion to do, ever.

Notice how wide the male range runs. A lab "reference range" is a statistical description of the population that lab tested — not a statement about what's healthy. That's why the top of the male range (566 ng/mL) sits far above the level at which the WHO says to start considering iron overload risk (200 µg/L in men).³ The two numbers answer different questions, and a result inside your lab's range can still be worth a conversation.

Why the low-ferritin threshold is disputed

This is the part most articles skip. 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? Because a very low ferritin is highly specific but poorly sensitive. A ferritin under 10–15 ng/mL is 99% specific for iron-deficiency anemia — if you're below it, you're deficient, essentially no exceptions.⁴ The problem is everyone it misses. Raising the cutoff to 30 ng/mL improves sensitivity from 25% to 92%, while specificity stays at 98% — a huge diagnostic gain for almost no cost in false positives.¹² That's the evidence behind the U.S. shift toward 30, and a Cochrane review conducted with the WHO likewise found a threshold around 30 µg/L both sensitive and highly specific in adults.⁷ The AGA pushes further to 45 ng/mL (85% sensitivity, 92% specificity) in patients who already have anemia.⁵

How much does this matter in practice? Enormously. In a national U.S. study of females aged 12–21, iron deficiency prevalence was 17% using a < 15 µg/L cutoff, 38.6% at < 25 µg/L, and 77.5% at < 50 µg/L.¹³ Same girls, same blood — the threshold alone swings the answer from "uncommon" to "most of them."

What this means for you: if your ferritin lands between roughly 15 and 45 ng/mL and you have symptoms of iron deficiency, you are in a genuine gray zone where your result may be labeled "normal" by your lab yet still be treated as deficient by many clinicians. That is a conversation worth having rather than a number to accept silently — especially since a low-normal ferritin plus a high RDW or a low MCV points strongly toward real deficiency.

Interpreting your results

Low ferritin: iron deficiency

A low ferritin is essentially always synonymous with depleted iron stores — it is the most specific marker of iron deficiency available.¹⁰⁷ Crucially, it can be low long before anemia appears, a state called iron deficiency without anemia. This is far from rare: in U.S. females aged 12–21 with iron deficiency, 83.6% did not have iron-deficiency anemia, meaning a hemoglobin-based screen would have cleared them.¹³

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

Symptoms — even without anemia — include fatigue, exercise intolerance and shortness of breath on exertion, hair loss, brittle nails, cold intolerance, poor concentration, and restless legs syndrome. That last one is well established: international guidelines recommend oral iron for restless legs when serum ferritin is ≤ 75 µg/L, and intravenous ferric carboxymaltose is effective in moderate-to-severe cases with ferritin < 300 µg/L — thresholds far above any "deficiency" cutoff, because the brain's iron needs aren't captured by the standard range.¹⁴

The most common causes:

• Blood loss — heavy menstrual periods (the leading cause in premenopausal women) and gastrointestinal bleeding (ulcers, polyps, colon cancer, NSAID use).
• Inadequate intake — diets low in bioavailable iron, including vegetarian and vegan patterns, where plant (non-heme) iron is absorbed less efficiently.
• Malabsorption — celiac disease, H. pylori infection, inflammatory bowel disease, and bariatric surgery, all of which impair iron uptake.
• Increased demand — pregnancy, growth spurts in children and adolescents, and endurance athletes, who lose iron through sweat, gut micro-bleeding, and foot-strike hemolysis.
• 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. U.S. guidance is unambiguous — all adult men and postmenopausal women with iron-deficiency anemia should be evaluated for gastrointestinal malignancy with bidirectional endoscopy, which finds colonic cancer in about 9% and upper GI cancer in about 2% of those patients.¹²⁵ This is not a test to postpone.

Low ferritin on your CBC. Iron deficiency leaves fingerprints across your complete blood count: a low MCV (small cells), a low MCHC (pale cells), a rising RDW (uneven cell sizes — often the earliest CBC change), and eventually a falling hemoglobin and red blood cell count. Iron deficiency is also a classic cause of reactive thrombocytosis, so a high platelet count alongside a low ferritin is a recognized pairing rather than a coincidence.

Treatment is your doctor's call, and it always has two halves: replace the iron (oral first, intravenous when oral fails or is not tolerated) and find out why it was lost. Taking iron without answering the second question can mask a bleeding lesion for months.¹⁰

High ferritin: causes and when to worry

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

• Inflammation or infection — ferritin rises alongside CRP. This is by far the most frequent explanation.
• Metabolic syndrome and fatty liver disease (MASLD) — obesity, insulin resistance, and type 2 diabetes all raise ferritin. Given U.S. prevalence, this is a leading cause of a mildly high result, often with a raised ALT.
• Alcohol use — a direct and often-overlooked driver.
• Liver disease — hepatitis, cirrhosis, and liver injury of any cause release ferritin.
• Chronic kidney disease and dialysis.
• Hereditary hemochromatosis — genuine iron overload, and the one cause you must not miss (below).
• Rarely, hemophagocytic lymphohistiocytosis (HLH) / macrophage activation syndrome, 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, not tumors. It is not a cancer screening test. Only a very high and unexplained ferritin prompts a broad hospital work-up spanning infection, blood disorders, autoimmune disease, and — among many other possibilities — malignancy.⁸ For a result slightly above the reference range, the sensible reflex is to look at CRP, transferrin saturation, alcohol intake, weight and metabolic markers, and liver enzymes — not to assume the worst.

When should you worry? The number alone doesn't decide. What matters is how high, the transferrin saturation, the CRP, your context (alcohol, liver, weight, kidney disease), and the trend over time. A modest elevation with a high CRP points to inflammation and should simply be rechecked once the inflammation has settled. A markedly or persistently elevated ferritin — especially with a high transferrin saturation — deserves a proper evaluation, without panic.

Hereditary hemochromatosis: the genetic cause

Hereditary hemochromatosis is the cause of high ferritin that most matters in the U.S., because it is both common in people of 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.¹⁵ 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, where C282Y is rare.¹⁵

In hemochromatosis, the body absorbs too much iron and deposits it in the liver, heart, pancreas, endocrine glands, and joints. Symptoms — fatigue, joint pain, abdominal pain over the liver, loss of libido or erectile dysfunction, and skin darkening — typically emerge after age 40, and about 10 years later in women than in men, because menstruation protects against iron accumulation until menopause.¹⁵

The key diagnostic point: ferritin alone cannot make this diagnosis. The diagnostic hallmark is a raised transferrin saturation, which reflects the underlying hepcidin deficiency; genetic testing for HFE confirms it.¹¹ This is precisely why a high ferritin should never be worked up in isolation — a high ferritin with a normal transferrin saturation points toward inflammation or fatty liver, while a high ferritin with a high transferrin saturation points toward iron overload. Treatment is straightforward and effective: therapeutic phlebotomy — removing about a pint of blood on a schedule until iron stores normalize.¹⁵¹¹

Ferritin, serum iron, and transferrin saturation

No one interprets ferritin by itself. The iron panel works as a set:

• Ferritin measures your stores — the tank.
• Serum iron measures the iron currently circulating — highly variable by hour and meal, and nearly meaningless alone.
• Transferrin and total iron-binding capacity (TIBC) measure the transport protein — capacity rises when iron is scarce.
• Transferrin saturation (TSAT) is the percentage of that capacity actually filled: low (< 20%) in deficiency, high in overload. It is the marker that separates the two directions when ferritin is ambiguous.⁴

Adding CRP to that panel is what lets your clinician tell a truly normal ferritin from an inflammation-inflated one.

What can affect your ferritin

Several factors shift ferritin or its interpretation — mention them to your clinician, because they change the reading:

• inflammation and infection — raise it, potentially masking deficiency;⁷
• obesity and metabolic syndrome — raise it, independent of iron stores;
• alcohol — raises it;
• liver disease, including fatty liver — raises it;
• chronic kidney disease — raises it and degrades its accuracy;⁵
• sex and age — men run higher; women rise after menopause;
• pregnancy — lowers it as demand climbs;
• recent iron supplementation or IV iron — raises it, sometimes dramatically;
• recent blood donation — lowers it;
• the lab's assay, which is why ranges differ between laboratories.²

When to see a doctor

Contact your clinician if your ferritin falls outside your lab's range, or if it sits low-normal (roughly 15–45 ng/mL) while you have symptoms of iron deficiency — fatigue, hair loss, restless legs, breathlessness on exertion. A low ferritin should prompt a search for the cause, and in men and postmenopausal women that means evaluating for gastrointestinal bleeding.¹² A high ferritin should be checked against your CRP and transferrin saturation before anyone draws conclusions; a high ferritin with a high transferrin saturation warrants testing for hemochromatosis.¹¹ Seek prompt care for visible 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 actively being renegotiated. A Cochrane review conducted with the WHO confirms that a ferritin threshold around 30 µg/L is both sensitive and highly specific for iron deficiency in adults, and that thresholds must be raised when inflammation is present.⁷ National U.S. data show why the choice is so consequential: prevalence in young females moves from 17% to 77.5% depending on whether you draw the line at 15 or 50 µg/L.¹³ (Weyand AC et al., JAMA, 2023 — DOI.)
• Iron deficiency is more common in U.S. adults than assumed — and often invisible. A 2024 NHANES analysis found 14% of U.S. adults with absolute and 15% with functional iron deficiency, with functional deficiency exceeding absolute deficiency in every group except women under 50 — and most of it occurring without anemia. Iron supplement use among those 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, recent work shows ferritin overestimates iron stores; transferrin saturation < 20% identifies functional deficiency far better.¹⁶ Major intravenous iron trials in heart failure — such as AFFIRM-AHF — rest on deficiency definitions that combine ferritin with saturation for exactly this reason.¹⁷ (Packer M et al., Circulation, 2024 — DOI.)
• Hyperferritinemia calls for a stepwise work-up. Recent reviews recommend a structured evaluation — transferrin saturation, liver panel, alcohol history, metabolic assessment, and HFE genetic testing when saturation is high — rather than repeating an isolated ferritin.¹⁸⁸ In hemochromatosis, ASH emphasizes that transferrin saturation, not ferritin, is the diagnostic hallmark, with phlebotomy remaining the mainstay of treatment.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. Remember the ballpark figures — females ~15–205 ng/mL, males ~30–566 ng/mL, varying by lab — that low ferritin means iron deficiency that must be explained rather than just supplemented, and that high ferritin is usually inflammation, fatty liver, or alcohol — not cancer. Know too that the "low" threshold is genuinely debated (15 vs 30 vs 45 ng/mL), so a low-normal result with real symptoms deserves a conversation. And because ferritin is also an inflammation protein, it is never read alone: its meaning comes from reading it with 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: