Ferritin
Ferritin is your body's iron savings account. It's usually the first number to drop when iron runs low, often months before anything else looks abnormal.
Part of the Iron Studies — see all 6 values together, including Iron, Total Iron-Binding Capacity, Transferrin.
If ferritin is flagged on your results, you're looking at one of the most informative numbers in routine bloodwork. Ferritin is a protein that stores iron, and the small amount circulating in your blood mirrors how much iron your body has put aside. Think of it as the balance of your iron savings account: serum iron shows what's in your wallet today, while ferritin shows what's in the vault.
That distinction matters because ferritin is usually the first marker to move when iron status changes. Stores get drained, or overloaded, months before hemoglobin or red blood cells show any change at all.
One small mercy before the numbers: ng/mL and µg/L are the same value, just labeled differently, so a 35 in either unit is the same result.
What the numbers usually mean
ng/mL (µg/L)The World Health Organization's threshold for iron deficiency in healthy adults. At this level the warehouse is essentially empty.
Often prints without a flag, yet symptoms and treatment response are common here. Many clinicians consider anything under about 30 a sign of deficiency.
Comfortable storage territory. Lab ranges top out near 300 for women and 340 for men, and your report's range is the one that applies.
Far more often inflammation than iron overload. Read together with transferrin saturation and CRP before drawing conclusions.
That 15–30 stretch deserves a sentence of its own. A ferritin of 25 in a menstruating woman often looks "normal" on the report, yet it's low enough to cause symptoms, and research on fatigue and hair shedding suggests benefits when stores are rebuilt to at least 30–50. If your result sits in the teens-to-forties and the symptom list below feels familiar, that's a conversation worth having with your doctor rather than a result to ignore.
What does low ferritin mean?
Low ferritin means your iron stores are running out. It is the earliest and most specific signal of iron deficiency, and if the drain continues long enough, hemoglobin eventually drops too and the diagnosis becomes iron-deficiency anemia.
The usual reasons stores get depleted:
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Blood loss
Heavy menstrual periods are the most common cause in women; slow, unnoticed bleeding from the gut (for example from regular anti-inflammatory painkiller use or, less often, conditions that need to be ruled out) is the classic cause in men and postmenopausal women.
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Not enough iron coming in
Vegetarian and vegan diets can absolutely be iron-sufficient, but they require more attention, since plant iron is absorbed less efficiently than iron from meat.
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Poor absorption
Celiac disease, inflammatory bowel conditions, prior stomach or intestinal surgery, and long-term acid-suppressing medication all reduce how much iron makes it from food into blood.
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Higher demand
Pregnancy, breastfeeding, growth spurts, frequent blood donation, and endurance training all draw down the account faster than usual.
Symptoms of low ferritin
Iron deficiency develops gradually, so the symptoms are easy to blame on life in general: persistent fatigue and low stamina even with decent sleep, hair shedding beyond the usual, pale skin, brittle nails, cracks at the corners of the mouth, feeling cold, breathlessness on stairs, restless legs at night, and the famous one, craving ice to chew. None of these are specific to iron. That's exactly why the ferritin number is useful: it turns a vague "I'm always tired" into something measurable and fixable.
What does high ferritin mean?
This is the part that confuses almost everyone: high ferritin usually isn't about iron at all. Ferritin is an acute-phase reactant, meaning it rises whenever the body is inflamed, regardless of iron stores. In practice an elevated result most often traces back to:
- inflammation or infection (anything from a recent illness to a chronic condition; checking CRP alongside helps)
- liver stress from fatty liver disease or regular alcohol
- the metabolic trio of excess weight, insulin resistance, and type 2 diabetes
When fatty liver is the driver, it usually shows up first as a mildly raised ALT, the enzyme liver cells leak when they are irritated.
The diagnosis doctors actually want to catch is the rarer one: hemochromatosis, an inherited condition where the gut absorbs too much iron for decades. It's very treatable when found early. The sorting tool is transferrin saturation: it stays normal when inflammation drives the ferritin up, and runs high in true overload. The iron saturation vs ferritin comparison shows how the two move together.
A repeat test after a few weeks, once any recent illness has settled, resolves a surprising share of "high ferritin" scares on its own. And when inflammation makes ferritin impossible to trust either way, the soluble transferrin receptor is the tiebreaker doctors reach for: it tracks how iron-starved the cells actually are and does not climb with inflammation.
How to raise low ferritin
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1
Find the leak first
If iron keeps leaving through heavy periods or gut loss, supplements alone are mopping the floor with the tap running. The cause needs attention too.
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2
Oral iron is the standard start
Classic dosing is daily, though absorption research suggests every-other-day dosing works comparably well with fewer stomach side effects. A schedule worth discussing with your doctor, since it's much easier to stick with.
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3
Help absorption along
Take iron away from coffee, tea, dairy, and calcium supplements; vitamin C (a glass of orange juice) modestly helps. Iron-rich foods such as red meat, liver, legumes, and dark leafy greens do the slow background work.
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4
Recheck in about three months
Ferritin moves slowly. Expect store rebuilding to take three to six months, and earlier retests to show mostly noise.
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5
IV iron exists for the hard cases
Poor absorption, intolerance to pills, or losses that outpace oral intake. That's a clinician's call.
If ferritin is high rather than low, the path runs the other way: don't supplement iron, address weight, alcohol, and liver factors with your doctor, and let them decide whether genetic testing for hemochromatosis or periodic blood removal (which is both the test and the treatment) is warranted.
Ferritin rarely travels alone
Ferritin is the headline, but the story needs the supporting cast. Serum iron, TIBC, transferrin, and transferrin saturation together form the iron studies panel, and hemoglobin tells you whether deficiency has progressed to anemia. Iron status even leaks into tests that look unrelated: depleted stores can nudge HbA1c upward without any change in blood sugar, one more reason a low ferritin is worth fixing. That quirk inflates only the three-month average; a direct glucose reading, which measures the sugar circulating at the moment of the draw, stays put. Low iron also raises how much lead the gut absorbs, which is why a heavy-metal workup and an iron panel are sometimes read together. The ferritin vs iron comparison explains the most common point of confusion, and the iron studies guide walks through reading the whole panel as one picture.
Because ferritin moves slowly and reflects stores, it's also an ideal marker to track over time. A ferritin of 60 means one thing if it was 20 last year and quite another if it was 150. Trend direction often says more than any single value.
Sources
- Ferritin Blood Test — MedlinePlus, National Library of Medicine
- WHO guideline on use of ferritin concentrations to assess iron status
- Iron-Deficiency Anemia — NHLBI, National Institutes of Health
- Hemochromatosis — NIDDK, National Institutes of Health
Written and reviewed by BloodSight Editorial Team · Last updated
See your Ferritin on one timeline.
BloodSight calibrates the reference range to your sex, age, and lab — and shows every value across every visit.
In your personal range
Normal ranges
| Group | Range | Unit |
|---|---|---|
| Adult Male | 24–336 | ng/mL |
| Adult Female | 11–307 | ng/mL |
Reference ranges may vary by laboratory and individual factors.
Ferritin — Common Questions
What is the difference between ferritin and iron?
Can ferritin be low without anemia?
How fast does ferritin rise with iron supplements?
Do I need to fast before a ferritin test?
Why is my ferritin high if I feel fine?
Disclaimer
This content is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment recommendation. Reference ranges may vary by laboratory. Always discuss your results with a qualified healthcare professional.
Related Tests
Serum iron looks like the headline iron number, yet it's the twitchiest value on the panel. It can read normal on the morning your iron stores hit empty.
Total Iron-Binding Capacity counts how many iron-carrying positions your blood is advertising. It's the iron panel's backwards number: the result climbs highest when iron is running out.
Transferrin is the protein that carries iron through your blood. Many labs never print it by that name, reporting its iron-carrying capacity as TIBC instead.
Iron saturation is the percentage of your iron carrier's seats that are filled. It's the one number on the panel that tells real iron overload apart from inflammation.
Soluble transferrin receptor is the iron test ordered when ferritin can no longer be trusted. Inflammation cannot push it up, so a high sTfR means cells are genuinely starved for iron.
Hemoglobin is a concentration, not a headcount of your red cells. It reads high when you are dry, low when fluid floods in, and can sit perfectly normal while your iron quietly runs out.
CRP confirms inflammation is somewhere in the body. It almost never says what is inflamed or where, and that limit is exactly why it stays one of the most-ordered blood tests.
One number that remembers everything: roughly three months of blood sugar, weighted toward recent weeks, immune to last-minute virtue. That long memory is also where the test can go wrong.
Glucose is a single photograph of your blood sugar, captured the instant the needle goes in. Whether you had eaten, the hour of day, even the stress of the draw can change what the picture shows.
ALT is the enzyme liver cells spill when they are injured. The blood level counts that damage rather than how well the liver works, which is why a hard workout or a new pill can lift it.
MCV is the average size of your red blood cells. Small cells lean toward iron trouble, large cells toward B12 or folate, and a crowd of both can average out to a number that looks fine.
A blood lead level is mostly a measure of the last few weeks. The CDC reference value tells you where you sit in the population, not whether you are safe.