You probably know the feeling of being tired for weeks and not knowing why. Many of us also glance at the numbers on a yearly blood panel without really reading them. One line on that panel is often misread or skipped entirely.
That line is ferritin. According to the NIH Office of Dietary Supplements, serum ferritin reflects your body's iron stores. A value below 30 micrograms per liter already suggests iron deficiency, and under 10 points to iron deficiency anemia.
That matters because the iron tank can run low long before the red blood cell count drops. By the time standard anemia tests look abnormal, the shortage has often been building for months.
What low ferritin means for your body
Iron is used for far more than hemoglobin. It drives muscle energy, hair follicles, mental focus and the brain pathways that control restless legs at night. When stores drop, those systems feel it first.
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Common signs of low ferritin include ongoing fatigue, hair shedding, poor exercise recovery, cold hands and feet, brittle nails, headaches and restless legs. Some people also develop a strong urge to chew ice, a pattern doctors call pica.
Where the ferritin line is drawn also matters. A 2024 study in JAMA Network Open compared the cutoffs used in primary care. Raising the threshold from 15 to 45 nanograms per milliliter uncovered about six times as many cases of nonanemic iron deficiency.
Normal ferritin ranges by sex and age
Reference ranges vary slightly between laboratories. Mayo Clinic labs use the ranges in the table below for most adults. Nanograms per milliliter equals micrograms per liter, so the two units are interchangeable.
| Group | Typical range (ng/mL) |
|---|---|
| Adult men | 12 to 300 |
| Adult women, before menopause | 12 to 150 |
| Adult women, after menopause | 12 to 263 |
| Suggests iron deficiency (NIH) | below 30 |
| Suggests iron deficiency anemia (NIH) | below 10 |
The wider range after menopause reflects monthly losses stopping, so iron stores often rise. Children and infants have their own age-specific values that doctors interpret differently.
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What a high ferritin reading may be telling you
A high result is not automatically dangerous. Ferritin rises during almost any kind of inflammation, so an infection, an autoimmune flare or a recent injury can push the number up for a while.
A persistently high reading is a different story. The Cleveland Clinic lists hereditary hemochromatosis, chronic liver disease, kidney disease, diabetes and some blood or liver cancers among the causes. Alcohol-related liver damage and fatty liver disease can also raise it.
Hemochromatosis is the condition doctors most often look for first. It is an inherited disorder in which the body absorbs more iron than it needs. Over time, the excess builds up in the liver, heart and pancreas.
Untreated, hemochromatosis can lead to cirrhosis, liver cancer and heart failure. Picked up early through ferritin and iron saturation, most patients manage it with regular blood draws to lower stores.
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How to use the number with your doctor
A single ferritin reading rarely tells the whole story. Doctors usually interpret it alongside serum iron, transferrin saturation and a complete blood count. Those tests together show whether the iron tank is empty, overloaded or distorted by inflammation.
If your ferritin is low and you have fatigue, hair loss or poor exercise tolerance, bring the number to your doctor before trying a supplement. If it is high, ask about a repeat test or an iron-saturation panel before any further workup.
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This article is made and published by Aksel Kryhlmand, who may have used AI in the preparation.