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What is ferritin?

Ferritin is the soluble, storage form of iron. As such, the ferritin measurement gives us an indirect measurement of your body’s iron stores. Low levels of ferritin may indicate depletion of iron stores (mild iron deficiency), iron-deficiency erythropoiesis (low red blood cell count), or iron deficiency anemia (low hemoglobin and hematocrit). Anemia is the most prevalent nutritional deficiency worldwide.

Why is ferritin important?

Iron is an important indicator of physiological health as it is extensively used in energy production and oxygen transport in the blood. Ferritin levels that are out of range can point to a variety of complications such as fatigue, headaches, restless legs syndrome, heart problems, pregnancy complications, and developmental delays in children. In addition, people with iron deficiency anemia are more likely to have weaker immune responses, gastrointestinal upset, problems with concentration and memory, and are less able to work, exercise, and control body temperature. As women are especially susceptible to low levels of iron, this test is particularly important for women’s general health. Heme iron (found in meat) is more bioavailable than nonheme iron (found in plants and fortified foods), so vegetarians are more prone to having depleted iron stores as well.

How can I better understand my ferritin levels?

Standard lab ranges for ferritin are currently quite broad. For example, the following are considered normal ranges according to:

  • Mayo Clinic: 24-336 ng/mL for males and 11-307 ng/mL for females
  • Cleveland Clinic: 30.4-565.7 ng/mL for males and 14.7-205.1 ng/mL for females
  • UCSF Health: 12-300 ng/mL for males and 12-150 ng/mL for females

Considering the link between ferritin and inflammation, as well as findings that levels under 50 ng/mL are associated with fatigue and above 150 ng/mL may indicate iron overload, SiPhox Health utilizes a more conservative optimal range between 50 ng/mL and 150 ng/mL.

As explained in Gastroenterology & Hepatology, while many laboratories consider serum ferritin levels > 200 ng/mL in females and > 300 ng/mL in males to be abnormal, these levels are common among the general population, likely due to the prevalence of obesity and fatty liver.

Abnormally low levels of ferritin may indicate iron deficiency at < 30 ng/mL and iron deficiency anemia at < 10 ng/mL.

It is important to note that serum ferritin levels may be elevated in the presence of the following conditions:

  • inflammation
  • significant tissue destruction
  • liver disease
  • malignancies such as acute leukemia and Hodgkin’s diseaserecent intravenous iron treatment or active oral iron supplementation.

Pregnant women, menstruating women, frequent blood donors, and people with cancer, gastrointestinal problems, and heart failure are most likely to have inadequate iron levels.

Does at-home collection change my ferritin result?

Slightly, and in a predictable direction. Ferritin measured from a capillary sample tends to run a little higher than ferritin from a standard venous draw taken at the same moment. Studies comparing the two side by side have found capillary values averaging roughly 3–5% higher, with the difference reaching statistical significance in paired adult and pediatric samples. Part of this is the collection method itself: one validation study of a capillary ferritin system attributed about 10% of total measurement variability to venous vs. capillary sampling alone.

The gap is small enough that capillary ferritin still performs well against lab standards: a 2025 comparison of 34 chemistry analytes found capillary ferritin stayed within desirable total error limits and met CLIA acceptance criteria. 

What this means practically: don’t read small differences between a SiPhox result and an older venous result as a real change in your iron stores. And if your result lands above the pay attention high ceiling, that’s worth a confirmatory venous draw before concluding anything about iron overload.

How can I maintain optimal ferritin levels?

If you have a known iron condition, start here

The guidance below is written for people with no diagnosed iron disorder. If any of the following applies to you, work from your clinician’s plan rather than this page.

Hemochromatosis or a known HFE variant. Don’t use iron supplements or high-dose vitamin C, which increases iron absorption. Blood removal for iron overload is therapeutic phlebotomy on a clinician-set schedule with its own ferritin targets, not something to self-manage through donation. Ferritin alone also isn’t how iron overload is diagnosed: transferrin saturation typically becomes abnormal before ferritin rises, and guidelines treat elevated transferrin saturation as the trigger for genetic testing, with ferritin measured alongside to improve accuracy. A high ferritin on its own is not a hemochromatosis diagnosis.

Diagnosed iron deficiency or iron deficiency anemia. Ferritin is raised by inflammation, so a normal-looking value can mask real deficiency. When inflammation is likely, ferritin should be interpreted alongside an inflammatory marker, and the deficiency cutoff raised accordingly. If your High Sensitivity CRP is elevated on this panel, treat a mid-range ferritin as inconclusive rather than reassuring.

Recent iron infusion or active supplementation. Intravenous iron raises ferritin sharply for weeks. In one trial, levels roughly doubled over four weeks of infusions and were still elevated two weeks after the last dose. A result in this window reflects the treatment, not your baseline stores. Ask your clinician when to retest.

If you have low ferritin, a few lifestyle modifications to try include:

Dietary Changes: Supplementing or consuming more iron (fortified cereals, oysters, lentils, etc.) alongside vitamin C (oranges, strawberries, tomatoes, etc.) can help to enhance iron absorption. Additionally, limit foods containing phytates, polyphenols, and high calcium that inhibit iron absorption (tea, coffee, red wine, calcium supplements) when consuming iron. Cooking with cast iron pans to increase the iron content of your meals can help as well.

If you have high ferritin, a few ways to lower levels include:

Dietary Changes: Decreasing consumption of fortified cereals, oysters, lentils, etc. can help decrease iron levels.

Lifestyle Changes: Limiting alcohol consumption and donating blood can lead to lower ferritin levels. If you have been diagnosed with iron overload, follow the phlebotomy schedule your clinician sets rather than donating on your own.

If your ferritin levels are abnormally high, it may mean you have hyperthyroidism, hemochromatosis (iron overload), liver disease, inflammatory diseases, an infection, or cancer, which is why it is important to consult with your physician if you are concerned about any of your results.

Where can I learn more?

DISCLAIMER: IF YOU ARE CONCERNED WITH ANY OF YOUR RESULTS, PLEASE CONSULT WITH YOUR PHYSICIAN.