What is ferritin and why is it important to your body?

Ferritin is a protein that’s produced in the body’s cells, and largely concentrated in the liver and immune system cells. Ferritin stores and releases iron, which is essential for producing red blood cells. With insufficient iron, your body can’t create enough hemoglobin — a key substance that allows the blood to circulate oxygen to your organs and tissues.

Iron deficiency anemia, which causes symptoms like fatigue and weakness, is a common medical condition. A ferritin blood test can help doctors diagnose iron deficiency anemia.

Some people, such as menstruating women or endurance athletes, are more likely to have low iron levels and related fatigue. Oftentimes, taking iron supplements or making dietary changes are all that’s needed to normalize ferritin levels.

In other cases, a low ferritin level is the first clue for doctors to identify and treat conditions like gastric bleeding. High ferritin, on the other hand, can be an indicator of several underlying medical issues. Here’s what experts want you to know about ferritin.

[See: Questions Doctors Wish Their Patients Would Ask.]

What Is Ferritin?

Ferritin actually represents the amount of iron that’s in your body overall, rather than what’s in your blood. Iron is stored in the liver, spleen, muscles and bone marrow.

“Ferritin is the surrogate measure for the body’s storage of iron — how much iron the whole body has on board — so it’s the blood test of what’s actually in the tissues,” says Dr. Janis Abkowitz, a professor of medicine and head of the division of hematology at the University of Washington School of Medicine, and a researcher and a physician at the Fred Hutchinson Cancer Center.

“Ferritin is the bricks for the warehouse of iron,” says Dr. Thomas DeLoughery, a professor of medicine in the divisions of hematology/oncology and laboratory medicine at Oregon Health & Science University. “A little bit of ferritin leaks out to the tissues and that’s proportional to how much iron stores you have in your body.”

When the body absorbs iron, it transfers the iron to the tissues that need it by putting out a molecule called transferrin, Abkowitz explains. Other blood tests such as serum iron or transferrin saturation also help provide a snapshot of the body’s iron content, such as the level of iron in the blood and the body’s ability to transport iron in the bloodstream.

[READ: The Most Iron-Rich Foods to Add to Your Diet]

Conditions Associated With Low Ferritin

Low ferritin levels may be behind a number of symptoms or conditions, including:

— Fatigue. The most common symptom of iron deficiency anemia is fatigue.

— Restless legs syndrome. RLS is a neurological condition that involves an uncontrollable urge to move your legs.

— Hair loss. Research has connected lower ferritin to hair loss in general, and in women in particular.

— Unusual food cravings or ice cravings. Pica, an urge to eat nonfood items like clay, may occur in pregnancy, which is associated with low ferritin levels.

— Decreased stamina in athletes. Endurance athletes in particular, such as long-distance runners or swimmers, can experience a reduced performance from iron deficiency.

What Is a Ferritin Blood Test?

A ferritin test is separate from a complete blood count, or a CBC. A CBC is a standard screening test requiring a small blood sample. If your CBC shows low hemoglobin, for example, or if you have signs of anemia or iron overload (too much iron), your healthcare provider will likely order a ferritin test, which also involves a small blood sample, to follow up.

Precise normal ranges for ferritin, which is measured in nanograms per milliliter of blood, vary from one medical organization to another. For instance:

— Cleveland Clinic lists a normal range of 30 to 565 ng/ML for men, and a normal range of 15 to 205 ng/ML for women.

— OHSU lists a ferritin count of less than 20 ng/mL as consistent with iron deficiency, and a ferritin count of 21 to 50 as possible iron deficiency. With a ferritin count over 200 ng/mL, iron overload is a possibility.

— The American College of Gynecology lists a ferritin level above 30 ng/mL as normal in pregnancy.

— The American Gastroenterological Association defines a ferritin level of less than 45 ng/mL as iron deficiency anemia.

— The Merck Manual lists a normal ferritin range of 30 to 300 ng/mL.

“Nobody agrees on normal levels of ferritin,” DeLoughery says. “That’s a raging controversy right now. One thing that’s very clear is that the range of normal in most laboratories is not appropriate. We use a cutoff of 50. Several randomized trials show that if you’re tired and have a ferritin below 50, once you get above 50, you feel better.”

In a study of French women ages 18 to 53, who were not considered anemic but who complained of fatigue, researchers found that fatigue decreased significantly for those who received iron supplements. The study concluded with a recommendation that iron supplementation should be considered for women with unexplained fatigue who have ferritin levels below 50.

Low Iron Symptoms

The ferritin test is considered the most reliable test for iron deficiency anemia. People with iron deficiency may experience symptoms such as:

— Excessive fatigue.

— Skin pallor.

— Weakness.

— Dizziness or lightheadedness.

— Chills.

— Chest pain or arrhythmia.

— Cold feet and hands.

— Bruises.

— Nail brittleness or spooning.

— Headaches.

— Tongue soreness.

About 17% of younger, premenopausal women in the U.S. are iron deficient, according to a study using data from the National Health and Nutrition Examination Survey, published in August 2021 by The Lancet. Up to 20% of women under 50 are iron deficient, according to the National Heart, Lung, and Blood Institute. Menstruation puts women at higher risk due to periodic blood loss. While estimates vary, iron deficiency in general is less common among men.

Reasons for Low Iron

“When we say low ferritin, it’s a measure of low iron stores,” DeLoughery says. “The next question is always: Why are the iron stores low? With women, you always think of periods. In older patients or men (it’s often) ulcers, GI bleeding or GI cancer.”

Athletes frequently have low ferritin levels. “Some studies have shown that up to 80% of athletic women, and maybe 20% to 30% of athletic men can have low iron stores,” DeLoughery says. “That’s because sometimes being in good shape leads to subtle GI iron loss. But also, it’s because if you’re training, you have mild inflammation that actually blocks the absorption of iron. That’s a common issue and many college and pro programs now screen their athletes for iron deficiency.”

Depending on the sport, training intensity and the individual’s health history — such as previous iron deficiency or current fatigue — athletes may be tested at yearly or more frequent intervals.

Who Needs Ferritin Tests?

Routine screening with ferritin tests is typically done for patients with risk factors for iron deficiency. For instance, someone who is pregnant needs iron to make red blood cells for themselves and the baby, which is why all prenatal vitamins have iron, Abkowitz explains.

You might have ferritin blood testing in situations such as:

— Pregnancy.

— Gastrointestinal surgery.

— Heavy menstrual bleeding.

— Being significantly underweight.

— Athletic program participation.

— Having anemia symptoms or signs.

— Fatigue while following a vegan or vegetarian diet.

Iron Deficiency Treatment

Iron deficiency can be treated through diet and iron supplements. Some people may be able to increase their iron stores through food changes alone. However, DeLoughery says. “Often, supplementation is required to catch up with iron deficits.”

Diet and Iron Deficiency

To maintain good iron stores in your body, you can start by incorporating more iron-rich foods into your meals. “One fact is that the iron in any type of meat is much better absorbed than iron in other stores like vegetables or legumes,” DeLoughery says.

Good dietary sources of iron include:

— Red meat and beef liver.

— Seafood like oysters, clams, sardines, tuna and mackerel.

— Poultry and eggs.

— Plant-based protein sources like beans, legumes and tofu.

— Cooked spinach.

— Dried fruits, nuts and seeds.

Antioxidant-rich foods like colorful veggies, fruits and berries can help your body better absorb iron.

Iron Supplements

Nutritional fixes alone may not be enough to reverse an iron deficiency. “It can be hard, because we only have a limited amount of ability to absorb iron,” DeLoughery explains. “If you’re already in the hole, it’s kind of hard to catch up. So, often, supplementation is required to catch up with iron deficits.”

Ferrous sulfate, a form of the mineral iron, is typically used in over-the-counter oral iron supplements. Iron supplements come in a variety of brands and several formats such as standard or extended-release tablets, or in liquid elixirs or drops. OTC iron tablets usually contain 325 milligrams of ferrous sulfate, of which a portion is what’s known as elemental iron. You should speak with your doctor about the specific iron formulation and dose that’s right for you.

Multivitamins do not always contain iron, so always check the label first. Prenatal vitamins, which are specifically formulated to meet the needs of pregnant women and their babies, include essential vitamins like folic acid and essential minerals like iron.

GI Conditions and Low Ferritin

“You can lose iron because you have bleeding in the GI tract, like with an ulcer or cancer,” Abkowitz says. For older men with iron deficiency anemia, for instance, doctors will promptly recommend a CT scan, endoscopy and colonoscopy procedures to find out where they’re losing the blood, and take steps to determine if they have a gastrointestinal condition such as diverticulitis, a polyp or GI cancer that needs to be managed, she says.

High Ferritin Levels

Ferritin tests can also identify too-high iron levels in the body. When your body stores too much iron, this needs to be evaluated and treated, because chronic excess iron can lead to serious medical problems such as liver disease, heart conditions and diabetes.

Iron overload can be genetic, known as hereditary hemochromatosis. Otherwise, in secondary hemochromatosis, medical conditions or medical treatments cause iron overload. These may include:

— Anemia medications.

— Blood transfusions.

— Iron injections or pills to treat iron-deficiency anemia, typically for people who can’t tolerate oral iron.

— Long-term kidney dialysis.

— Liver diseases such as fatty liver disease or hepatitis C infection.

Certain patients are at ongoing risk of iron overload because of these conditions:

— Hereditary hemochromatosis, which is caused by inherited gene mutations. If you have this familial condition, your body absorbs too much iron from food. Therapeutic phlebotomy is a treatment in which blood is drawn to remove excess iron when needed as indicated by ferritin and iron levels.

— Secondary hemochromatosis can result in patients who need multiple blood transfusions for certain types of anemia, such as sickle cell disease and thalassemia. Iron chelation treatment involves injected or oral medication that binds to iron and removes it from the body through urine.

In general, iron-reduction or preventive actions include:

— Avoiding iron in forms such as iron pills or injections, multivitamins with iron and iron-fortified foods.

— Avoiding shellfish or fish that are raw or undercooked, which may cause infections that affect iron levels.

— Limiting alcohol for liver protection.

— Limiting vitamin C, which enhances iron absorption in the body.

High ferritin levels are not as clear-cut as low ferritin levels, and so medical evaluation becomes more complicated. “Certain things can make the ferritin inappropriately high,” Abkowitz says.

Inflammation from conditions like viral infections and fever, rheumatoid arthritis and inflammatory cancers may contribute to elevated ferritin.

High Ferritin Causes

A variety of medical conditions may cause abnormally high ferritin levels. These include:

— Viral infections.

— Cancer such as pancreatic, colorectal, lung, T-cell lymphoma, and liver cancer.

— Hodgkin’s lymphoma and leukemia.

— Hereditary and secondary hemochromatosis (iron overload).

— Autoimmune conditions like rheumatoid arthritis and thyroid disease.

— Liver disease.

— Adult-onset Still’s disease (a rare type of inflammatory arthritis).

— Type 2 diabetes.

Iron Overload Damage

Getting to the root of high ferritin levels is important. “When the ferritin is high, it means your whole body has too much iron,” Abkowitz says. “But it doesn’t tell you which organ has too much iron. Is there too much iron in the liver? Is it in the heart, where it’s devastating? It’s where it’s distributed that affects you.”

In physicians facing this patient scenario, “That’s where a study called an MRI T2* study comes in, if you’re concerned about which organ the extra iron is in, and what damage it is doing to that organ by virtue of being in a place where it shouldn’t be,” Abkowitz says.

Determining the location of excess iron is a major treatment factor.

Symptoms of High Ferritin

Although many people with iron overload don’t have symptoms, symptoms like these may arise:

— Fatigue.

— Weakness.

— Heart palpitations.

— Knuckle pain (‘iron fist’).

— Unexplained weight loss.

— Stomach pain.

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