How to track your ferritin over time

Ferritin is the test most people meet when they feel tired and someone checks their iron. It is also the one that most often comes back “normal” for people who are, in fact, low on iron. Part of that is the test, and part of it is the range printed next to it. A single ferritin answers one narrow question about one day. A run of them shows whether your stores are falling, whether iron treatment is filling them, and how long they stay full once you stop.

What ferritin measures

Ferritin is the protein your body stores iron in. Most of it sits inside cells in the liver, spleen, and bone marrow, but a small amount circulates in the blood, and that amount rises and falls with how much iron you have stored. The WHO guideline on ferritin calls it a good marker of iron stores and the test to use for diagnosing iron deficiency in otherwise healthy people.

That last part matters. Ferritin is also an acute-phase reactant: it goes up with inflammation, infection, liver disease, and a few other conditions, whether or not your iron stores have changed. A low ferritin almost always means low stores. A normal or high ferritin means low stores are less likely, but it does not rule them out if something else is pushing the number up.

Ferritin usually comes with other iron tests, often as an “iron panel” or “iron studies”:

• Serum iron: the iron circulating right now, bound to transferrin.
• TIBC or transferrin: how much iron your blood could carry.
• Transferrin saturation (TSAT): serum iron as a share of that capacity.

Serum iron and TSAT change much more from day to day and with recent meals and supplements. Ferritin is the steadier of the group and the one most worth charting. It also pairs naturally with hemoglobin from a blood count, since iron deficiency runs out of stores first and lowers hemoglobin later.

The numbers on the report

In the United States, ferritin is reported in ng/mL. Much of the world uses µg/L. They are the same number: 30 ng/mL is 30 µg/L. A few labs report pmol/L, which is different. The MSD Manual SI converter gives the factor:

pmol/L = ng/mL × 2.247

If any of your results are in pmol/L, convert them before you chart them, or the line will more than double at the switch.

The range on the report is not the cutoff

The reference range a lab prints for ferritin is usually the middle 95 percent of results from a population. That is a poor way to find iron deficiency, because the condition is common. The American Society of Hematology estimates that it affects about 14 percent of adults and 40 percent of females of reproductive age, so a range built from “typical” people includes many who are deficient. Ranges also differ between labs and by sex, which is why the same value can be flagged at one lab and pass at another.

Clinical cutoffs have been moving up for years. The WHO’s 2020 guideline kept the long-standing threshold of below 15 µg/L for healthy adults, and below 12 µg/L for young children. The AGA’s 2020 guideline on evaluating iron deficiency anemia used below 45 ng/mL instead, after finding that 15 missed many cases. In September 2026, the ASH guidelines for diagnosis of iron deficiency set new thresholds and asked labs to adopt them on their reports:

These apply when there is no inflammation, except for the last row. The ASH press release describes them as diagnostic cutoffs, not reference ranges.

For tracking, this means two things. Your lab’s flag may still be based on an older range, so a ferritin of 20 can print without an “L” next to it. And when you read an old result, read it against the cutoff your clinician uses now, not the range that was printed at the time.

How often it is tested

Ferritin has no fixed screening schedule. It is usually ordered for a reason:

• Symptoms or a low hemoglobin: to find out whether iron is the cause.
• Known risk: heavy periods, pregnancy, frequent blood donation, a gut condition that limits absorption, or a diet with little iron.
• During iron treatment: to see whether stores are filling.
• Suspected iron overload: usually with transferrin saturation.

During treatment, the first check is often of hemoglobin rather than ferritin. The British Society of Gastroenterology guideline recommends checking for a hemoglobin response within the first four weeks of oral iron, and continuing iron for about three months after hemoglobin returns to normal to refill stores. After that, it suggests periodic blood counts, perhaps every six months at first, to catch a relapse.

That means many people have a cluster of ferritin results during a deficiency and long gaps between. The result from three years ago, before your first low value, is often the most useful one you have. How to get all of your medical records covers tracking down the older ones.

What counts as a real change

Ferritin moves a fair amount from week to week in healthy people. In one study of 22 adults sampled weekly for five weeks, within-person variation was about 17 percent, and the change needed between two results before it was likely to be real was about 48 percent. Other studies, with different designs, have found more variation, not less.

In practice:

• A ferritin of 40 followed by 55 is within the range of ordinary noise.
• A ferritin of 60 followed by 25 is a change worth asking about, especially if hemoglobin moved too.
• Three results stepping down over a year say more than any single pair.

Two questions help sort it out:

• Were you sick, injured, or inflamed? See the next section. A sudden rise is often this, not more iron.
• What happened in the months before? Stores fill and drain over months. A new supplement started two weeks ago has barely had time to show.

When ferritin can mislead

Because ferritin rises with inflammation, a “normal” value can hide low stores. The WHO guideline lists inflammation, liver disease, obesity, and some rare blood conditions as causes of a raised ferritin, and recommends checking for inflammation alongside it. It suggests that in someone with infection or inflammation, a ferritin below 70 µg/L in adults may still indicate deficiency. ASH’s newer guideline uses ferritin below 100 or TSAT below 20 percent for adults with inflammation.

Things that can push ferritin up without adding iron:

• A recent infection, injury, or surgery.
• Chronic inflammatory conditions, such as inflammatory bowel disease or rheumatoid arthritis.
• Liver disease, including fatty liver and alcohol-related liver disease. The ACG hemochromatosis guideline notes these are more common causes of a high ferritin than inherited iron overload. If your ferritin and liver enzymes rose together, How to track your ALT over time is worth a look.
• Regular heavy drinking.
• Kidney disease. The AGA guideline notes ferritin may not reflect stores in chronic kidney disease. How to track your eGFR over time covers that side.

For this reason the WHO recommends measuring a marker of inflammation, such as C-reactive protein (CRP), alongside ferritin. If your history includes one, keep it next to the ferritin from the same draw.

Things that drain or fill your stores

Ferritin changes slowly with the balance between iron in and iron out.

• Menstruation. Monthly blood loss is the main reason iron deficiency is so common before menopause, and heavy periods are a major cause. Your cycle shows up in your labs covers the evidence. Ferritin itself shifts less across the cycle than serum iron and TSAT do.
• Pregnancy. The growing baby and placenta draw heavily on iron stores. ASH recommends a threshold of 30 ng/mL in pregnancy and recommends against the older 15.
• Blood donation. In a randomized trial of blood donors, donors who took a low-dose iron pill recovered their iron stores in a median of 76 days. Without iron, two thirds had not recovered them 24 weeks after a single donation. U.S. rules allow whole blood donation every 8 weeks, so frequent donors can drift down over years.
• Endurance training. A 2019 review found iron deficiency in roughly 15 to 35 percent of female athlete groups and 5 to 11 percent of male ones, and points to exercise-driven rises in hepcidin, the hormone that limits iron absorption.
• Gut conditions that reduce absorption, and blood loss from the gut. In men and postmenopausal women, the AGA recommends looking for a gut source of iron deficiency anemia.
• Iron supplements and infusions. Oral iron raises stores over months. Intravenous iron fills them much faster, often in one or two infusions. A ferritin drawn soon after an infusion reflects the dose you were just given more than a settled level, so ask when to recheck.

A treatment that works shows up in hemoglobin first, within weeks, and in ferritin over the following months. Did the medication actually do anything? covers reading a before-and-after fairly.

Low iron also affects other tests. Iron deficiency anemia can push A1c up, and treating it can bring A1c down with no change in blood sugar. How to track your A1c over time has more.

High ferritin and iron overload

A high ferritin is more often inflammation, liver fat, or alcohol than too much iron, but it can mean iron overload. The WHO guideline says a ferritin above 150 µg/L in menstruating women, or above 200 µg/L in men and in women who do not menstruate, may indicate a risk of overload in otherwise healthy adults. It also says ferritin should not be used alone to judge overload.

Transferrin saturation is the partner test. In hereditary hemochromatosis, the EASL guideline uses TSAT above 45 percent with ferritin above 200 µg/L in women, and TSAT above 50 percent with ferritin above 300 µg/L in men and postmenopausal women, along with genetic testing. Treatment is regular blood removal, and EASL’s targets are a ferritin below 50 µg/L during the first phase and below 100 µg/L for maintenance. The ACG guideline adds that a ferritin below 1,000 ng/mL at diagnosis points to a low risk of advanced liver scarring.

For anyone treated this way, ferritin becomes a test with a goal, checked on a schedule, much like A1c. It is one of the clearest cases for a chart with your own target range drawn on it.

What to record with each result

For each ferritin, keep:

Ferritin appears under a few names, such as Ferritin, Serum Ferritin, and “Ferritin, Serum”. Pick one and use it everywhere, or your history will split into short, separate lines.

Charting it

A simple line chart works. A few choices make it honest:

• Draw your threshold, not just the lab range. If your clinician uses 30 or 50, a chart shaded from 10 upward makes a falling line look fine.
• Use a log scale if your values span a wide range, such as during an overload treatment, so the low end does not flatten into the axis.
• Put hemoglobin on the same timeline. Ferritin falls first and hemoglobin later. Treatment reverses the order.
• Mark iron treatment and any infusion, and read the next few results with the months-long refill in mind.
• Mark illnesses and other inflammation, so a sudden spike has its explanation next to it.
• Space points by date. Monthly checks during treatment and a three-year gap should not look evenly spaced.

How to track your lab results over time has the general method for any test.

Tracking ferritin in HealthViewer

HealthViewer is a lab results tracker that runs on your own computer. It imports ferritin from lab report PDFs, MyChart downloads, and direct connections to your health system. Results named Ferritin, and ferritin sent by your health system under its standard code, file under one test, and ng/mL and µg/L share a chart as the same unit. A name like “Ferritin, Serum” can arrive as a separate test. Combine them with Merge… in the Test Catalog to get one line. Results in pmol/L are not converted, so convert those by hand before you compare.

In Trends, the Iron tag pulls together iron, ferritin, TIBC, and transferrin saturation, and the Iron Studies panel filter does the same for the panel. The overlay view puts ferritin and hemoglobin on one chart, and medication markers show when an iron supplement started or stopped. Add a journal entry for an infusion, a blood donation, or an illness, then turn on Show journal to see it on the chart. Set your threshold as a custom range in the Test Catalog, and the chart shades your target instead of the lab’s range.

Everything stays in an encrypted file on your computer, with no account and no cloud service. Getting Started walks through the first import.

This post is general information, not medical advice. Talk to your clinician about what your ferritin means for you and before starting or changing iron.