DoctorAIFerritin and iron studies are blood tests that show how much iron your body has stored and how much is available in the blood. Doctors use them to look for the cause of anemia, tiredness or pale skin, to check for iron deficiency and, less often, to look for too much iron in the body.
What iron tests measure
Conventional units come first, with SI units in brackets. These are typical adult ranges. Ferritin in ng/mL is the same number as µg/L. Your report will print its own ranges.
| Marker | What it is | Typical adult range | If higher | If lower |
|---|---|---|---|---|
| Ferritin | A protein that stores iron, so it reflects your iron reserves | Men: 24 to 336 ng/mL (24 to 336 µg/L). Women: 11 to 307 ng/mL (11 to 307 µg/L) | Often a sign of inflammation, infection, liver disease, alcohol use or excess weight, because ferritin rises with these. Less often it reflects too much iron in the body. | Can be a sign that iron stores are low, for example from blood loss such as heavy periods or bleeding in the gut, low iron intake, poor absorption or pregnancy. |
| Serum iron | The iron circulating in the blood right now | 60 to 170 µg/dL (10.7 to 30.4 µmol/L) | Recent iron supplements or an iron-rich meal, too much iron in the body, liver disease or red cells breaking down. | Iron deficiency, long-term inflammation or blood loss. |
| Total iron-binding capacity (TIBC) | How much iron your blood proteins (transferrin) could carry | 240 to 450 µg/dL (43 to 81 µmol/L) | Often rises when iron stores are low, and also in pregnancy or with oral contraceptives. | Too much iron in the body, inflammation, malnutrition or some liver and kidney conditions. |
| Transferrin saturation | Serum iron divided by TIBC, as a percentage | About 20 to 50% | May suggest too much iron in the body, or a recent iron supplement. | Below about 20% can suggest iron deficiency. It is also lower with inflammation. |
Many doctors treat a ferritin below 30 ng/mL (30 µg/L) as a sign of iron deficiency in adults, even when it sits above the lowest value printed on the report. Thresholds differ between guidelines, so discuss your own result with your doctor.
Why your lab's range may differ
Ferritin ranges differ between labs and between men and women, and the lowest printed value is not always the level at which symptoms start. Iron levels in the blood also swing during the day and from day to day. Use the range on your report, and treat the table above as a rough guide.
What can affect your results
- Iron supplements and meals: serum iron can rise for many hours after a supplement or an iron-rich meal. Labs often ask for an overnight fast and a pause on iron tablets beforehand, so follow your instructions.
- Time of day: serum iron tends to be higher in the morning.
- Inflammation and infection: ferritin rises as part of the body's response, so it can look normal or high even when iron stores are low.
- Periods, pregnancy and blood donation: all lower iron stores.
- Liver disease and alcohol: both can raise ferritin and serum iron.
- Recent transfusion: this can change iron results for some time.
How the results fit together
- Low ferritin with low hemoglobin and small red cells (low MCV) is the typical pattern of iron-deficiency anemia. See CBC results.
- Low ferritin with normal hemoglobin means iron stores are low before anemia has developed. This can still go with tiredness.
- Low serum iron and low transferrin saturation with a normal or high ferritin and a low or normal TIBC can suggest anemia linked to long-term inflammation.
- A persistently high ferritin together with a high transferrin saturation may lead your doctor to check for iron overload conditions such as hemochromatosis.
- When iron is low, doctors also look for the reason, such as blood loss or poor absorption. Because iron supplements have side effects and too much iron is harmful, they are usually started after a deficiency is confirmed.
When to contact a doctor
Low iron is common and treatable, but the cause matters. Contact your doctor if a result is flagged and you have:
- ongoing tiredness, paleness, breathlessness on light activity or a fast heartbeat
- heavy or long periods
- black, tarry or bloody stools
- for a high ferritin, joint pain, stomach pain or unusual fatigue
Seek urgent care for chest pain, fainting, severe breathlessness, vomiting blood or passing a large amount of black or bloody stool. Iron tablets can poison young children, so if a child may have swallowed some, call emergency services or your poison control center right away. In an emergency, call your local emergency number.
Frequently asked questions
What is a normal ferritin level?
Typical adult ranges are about 24 to 336 ng/mL for men and 11 to 307 ng/mL for women, though labs differ. Many doctors consider a ferritin under 30 ng/mL a sign of low iron stores. Because ferritin rises with inflammation, a normal value does not always rule out low iron.
What does low ferritin mean?
Low ferritin can be a sign that your iron stores are low. Common reasons include blood loss such as heavy periods or bleeding in the gut, not getting enough iron from food, poor absorption and pregnancy. Your doctor will usually look for the cause as well as decide on treatment.
What does high ferritin mean?
High ferritin is more often caused by inflammation, infection, liver disease, alcohol use or excess weight than by too much iron. If it stays high, especially with a high transferrin saturation, your doctor may check for iron overload conditions such as hemochromatosis.
Do I need to fast for an iron test?
Often yes. Serum iron can rise after a meal or an iron supplement, so many labs ask for an overnight fast and a pause on iron tablets for about a day, and prefer a morning sample. Ferritin alone is less affected. Follow the instructions you were given.