Ferritin (Blood)

Serum ferritin level

This test measures how much iron is in your blood.

Ferritin is a protein that stores iron. Red blood cells need iron to form normally and carry oxygen around your body. Other parts of your body, such as your liver, bone marrow, and muscles, also need iron.

Low levels of ferritin lead to iron-deficiency anemia. This means you have too few red blood cells. Iron deficiency can come from a poor diet or blood loss. Or your body may have trouble absorbing iron from food. It would take a very poor diet for a healthy adult to get a nutritional iron deficiency. But a low iron level is the most common nutritional deficiency in children. Children need extra iron during times of rapid growth.

In adults, low iron levels usually happen because of long-term (chronic) blood loss. If you have ulcers or tumors in your gut, intestinal bleeding, or very heavy menstrual periods, you could lose more iron than you take in and develop an iron deficiency. This can also happen if you are pregnant or breastfeeding.

High levels of iron can damage your joints, heart, liver, and pancreas. Too much iron is most often caused by an inherited disease called hemochromatosis. Many people with this disease never have any symptoms, especially women who lose iron through menstruation. But men and some women slowly build up excess iron over the years. They may begin to feel joint and belly pain in their 20s or 30s. Heavy alcohol use increases the amount of iron that is absorbed.

Iron poisoning happens when a large amount of iron is taken in all at once. This happens to children who accidentally take too many iron supplements. 

You may need this test if your healthcare provider thinks that you have low iron levels. Symptoms include:

• Pale or yellow skin

• Extreme tiredness and dizziness

• Weakness

• Heavy menstrual cycles

• Bleeding in your digestive tract

• Blood in your stool

• Shortness of breath or chest pain, especially with activity

• Brittle nails or loss of hair

• Pounding or "whooshing" sound in your ears

• A sudden spinning sensation (vertigo)

Children who eat a lot of ice and toddlers and babies who drink too much whole cow's milk may also get this test.

You might also have this test done to check your ferritin level after treatment for iron deficiency.

Your healthcare provider may also order other blood tests. These include:

• Serum iron level to measure the iron in the liquid part of your blood.

• Total iron binding capacity (TIBC) to measure the amount of transferrin in your blood. Transferrin is the protein that carries ferritin from the gut to the cells that need it.

• Hemoglobin and hematocrit to measure the number of your red blood cells.

• Complete blood count (CBC) to look at many different qualities of your blood, including the size of cells.

• HFE gene test to see if you have hemochromatosis.

• Zinc protoporphyrin to measure iron deficiency or levels of lead toxicity.

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in nanograms per milliliter (ng/mL). The normal range for ferritin in your blood serum is:

• 24 to 336 ng/mL for adult males

• 24 to 307 ng/mL for adult females

• 25 to 200 ng/mL for newborns

• 200 to 600 ng/mL at 1 month old

• 50 to 200 ng/mL at 2 to 5 months old

• 7 to 140 ng/mL for children 6 months to 15 years

If your results are lower, it may mean that you have iron-deficiency anemia. Lower levels may also be caused by certain medicines. Antacids can cause absorption problems, and nonsteroidal anti-inflammatory medicines can cause blood loss in your digestive tract.

If your results are higher, it may mean you have:

• Hyperthyroidism

• Hemochromatosis

• Liver disease

• Inflammatory diseases

• An infection

• Cancer, such as leukemia, lymphoma, or breast carcinoma

You may also have higher levels if you are getting iron-replacement therapy or had a recent blood transfusion.

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. 

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

Eating foods that are high in iron, including meat, leafy green vegetables, and beans, or taking iron supplements can affect your results. Drinking a lot of milk, donating blood frequently, and running long distances regularly can also affect your results.

You don't need to prepare for this test. Be sure your healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.