By Amanda Schupak, CNN
More people are low in iron than in any other micronutrient, according to the American Society of Hematology. But many live with fatigue, weakness, brain fog and other symptoms for months or years before a deficiency is caught.
Nearly one-third of adults in the United States may be iron deficient, according to a 2024 study. And routine screening among children and pregnant women — who are at high risk — may miss more than 70% of cases.
Some people online are self-diagnosing, citing dark under-eye circles and pale skin as evidence that they are low in iron. Social media influencers call the look “ferritin face,” named after a protein that stores the element in the body.
Iron deficiency is common, prevalent and underrecognized, said Dr. Ariela Marshall, associate professor of medicine at the University of Minnesota. New diagnostic recommendations, which ASH released in September, aim to ensure more patients secure early treatment.
Anemia is a condition that occurs when there are not enough red blood cells to carry oxygen to the body’s organs and tissues. Patients with anemia may feel tired, dizzy or short of breath, and they may have heart palpitations, cold hands and feet, pale skin, brittle nails or hair loss.
Anemia is often caused by a lack of iron, which supports brain and muscle function and is used to make hemoglobin, the molecule that transports oxygen in the blood. Stored in the protein ferritin, iron is recruited to make the hemoglobin in new red blood cells. When ferritin is low, it means there isn’t enough iron available to make red blood cells, which can lead to anemia.
But iron deficiency can cause the same sorts of symptoms without affecting hemoglobin or red blood counts. Having low iron can also cause restless leg syndrome and pica — cravings for nonfood items such as ice or clay. (Doctors are not sure why; it may be a sign that the body is seeking out iron from the environment.)
It is “a common misperception” that iron deficiency without anemia can’t cause symptoms, “and one that we definitely need to correct,” Marshall said.
Standard blood tests that count how many red blood cells a person has won’t catch iron deficiency that has not progressed into anemia.
“The symptoms of iron deficiency can be very subtle, or they can be attributed to many different things,” said Dr. Jacquelyn Powers, section chief of hematology at Texas Children’s Hospital and lead author of the 2026 guidelines. “Providers are not always thinking, ‘Oh, I need to check iron labs.’”
The amount of iron in a person’s blood cannot provide an accurate diagnosis of deficiency because it will vary depending on what they have eaten and how recently. Ferritin tests are the gold standard for assessing iron levels, Powers said. But until now, there has not been a single agreed-upon results threshold to determine who has iron deficiency.
The World Health Organization recommends using a ferritin concentration below 15 ng/mL for diagnosing school-age children and adults with iron deficiency. But researchers have questioned that math, expressing concern that such a low threshold misses many people whose iron stores are higher than that but still insufficient.
Some blood-testing laboratories use even lower cutoffs, meaning some patients’ lab tests may come back as “normal” even if their ferritin levels are very low.
The new ASH guidelines establish 20 ng/mL or less as the appropriate cutoff for children, 30 ng/mL for most adults, and 50 ng/mL or less for those with heavy menstrual bleeding or other risk factors such as a vegan diet or long-term antacid use for reflux. For adults with inflammatory issues, the new limit is 100 ng/mL, and the group suggests an additional test, called transferrin saturation.
“One of the goals of the guidelines was to highlight why testing for iron deficiency — regardless of whether the patient is anemic or not — is important because there are interventions that you can do to prevent later complications and address more subtle symptoms,” Powers said.
People with iron deficiency may have “a whole range of symptoms, from tiredness and fatigue to brain fog or cloudy thinking to feeling like you want to chew on things like ice,” Marshall said. “Somebody can have all of those. They can have one of them. They can have none of them.”
Social media posts claim that the signs of iron deficiency, including a pale complexion, hair loss and dry skin are identifiable as ferritin face. But Powers and Marshall were skeptical that it is possible to diagnose low iron via selfie.
Though some people with restrictive diets may have trouble getting enough iron each day, Marshall said that isn’t usually the cause of deficiency in the US. More common causes are blood loss and digestive conditions.
Women are more likely than men to have iron deficiency because of the loss of blood that comes with menstruation. Women who experience heavy periods are particularly susceptible.
Children and pregnant people are also at higher risk for iron deficiency because they use a lot of iron for growth and development. Rates of iron deficiency among pregnant people increase every trimester, Powers said.
People with chronic gastrointestinal conditions such as irritable bowel syndrome and Celiac disease may not be able to absorb enough of the iron they get from their diet. Deficiency may also come about from gastrointestinal blood loss, which can be an early sign of colon cancer.
Endurance athletes require more iron than most people, so they are also more likely to be deficient. One of the signs of deficiency is not being able to exercise as hard as you used to.
If a person eats well, gets good sleep and is “doing everything else that you associate with optimal health, but they’re still really tired, then I think it’s very reasonable to check their ferritin,” Powers said. “It’s an easy test, and there’s an easy intervention.”
Taking oral iron supplements can alleviate symptoms in weeks or months. If that course of action helps, it means low iron was contributing to your health problems. But it’s important to work with your doctor to figure out why your iron levels were low to begin with, Marshall said.
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