New guidelines raise the ferritin cutoff for iron deficiency to 30 ng/mL in adults and 50 with heavy periods

A woman whose blood test shows a ferritin of 25 has, until now, often been told her iron is fine. Under guidelines from the American Society of Hematology (ASH), she would be diagnosed with iron deficiency. The guideline, the society’s first on how to diagnose the condition, was published in the journal Blood Advances on August 24 and announced on September 16. It sets the cutoff for adults at 30 nanograms per milliliter, twice the figure the World Health Organization has long used for women.

The change drew wide attention in early October 2026, helped along by social media. Even before the guideline appeared, NBC News reported, TikTok influencers turned “ferritin face” into a viral trend, blaming it for a whole range of symptoms. The phrase is used in posts that attribute signs such as pale skin, fatigue, bloating or losing hair to low iron stores.

What ferritin measures in iron deficiency

In the society’s description, iron is stored in the protein ferritin and is essential for producing hemoglobin, the molecule in red blood cells that carries oxygen. A small amount of ferritin circulates in blood, and that amount tracks the size of the reserve. “Ferritin is a protein that stores iron in our bodies and is a reflection of how much iron storage we have,” Angela Weyand of the University of Michigan Medical School, a member of the guideline panel, told TODAY.

Iron deficiency and anemia are different stages of one process. When iron intake falls short or blood is lost, the body draws on its stores first, and ferritin falls. Only later does the supply of hemoglobin drop, and that later stage is iron deficiency anemia.

The distinction matters for testing. A routine complete blood count checks only for hemoglobin to determine anemia, but because the test does not check ferritin levels, a normal result would not rule out iron deficiency. “Iron is essentially a building block for the red cells, so somebody can be low on iron and not yet have developed anemia,” said Ariela Marshall, a hematologist at the University of Minnesota who spoke to NBC as an expert for the society.

Ferritin is reported in nanograms per milliliter, written ng/mL, or in micrograms per liter. The two units give the same number.

The new ferritin thresholds for iron deficiency

The guideline panel was assembled by the society and, according to the published report, included one patient representative and was balanced to minimize potential bias from conflicts of interest. A team at the University of Kansas Health System carried out systematic reviews of studies up to July 2025. The recommendations were graded with a standard method for rating evidence, then opened to public comment.

The panel agreed on 5 recommendations. The society listed the numerical cutoffs in its announcement.

Group	Ferritin level that defines iron deficiency
Children aged 9 months to 4 years	20 ng/mL or lower
Adults, including those who menstruate or are pregnant	30 ng/mL or lower
Higher-risk groups	50 ng/mL or lower
Adults with inflammation	Under 100 ng/mL, or transferrin saturation under 20%

The higher-risk category is described as including individuals with heavy menstrual bleeding and pregnant individuals with anemia. The inflammation category takes in adults with cancer, inflammatory bowel disease or infectious disease.

Inflammation needs its own rule because it distorts the test. Ferritin can increase in response to inflammation, so a person who is ill can have depleted iron stores behind a normal-looking number. For them the guideline allows a second measure, transferrin saturation, which shows how much of the blood’s iron-transport protein is carrying iron. The cutoff for that group is serum ferritin under 100 ng/mL or transferrin saturation of under 20%.

The stated aim is to prioritize the diagnosis of iron deficiency, irrespective of the presence of anemia. “These updated ferritin thresholds provide clear guidance in an area where consensus has been lacking,” said Jacquelyn Powers, who chaired the panel and is section chief of hematology at Texas Children’s Hospital.

Why the ferritin cutoffs were raised

The panel’s starting point was blunt. Existing guidance on how to diagnose iron deficiency is limited and not evidence based, the guideline says.

The best-known earlier numbers came from the World Health Organization: below 12 for young children and below 15 for women. Researchers at the US Centers for Disease Control and Prevention (CDC) noted in 2021 that those thresholds were ones which were developed on the basis of expert opinion.

Laboratories have their own problem. Most print a “normal range” beside each result, and that range is usually derived from the spread of values in people presumed to be healthy. NBC cited typical ranges from the Cleveland Clinic that run from 15 to 205 ng/mL in women, and from 30 to 566 ng/mL in men. If many of the women used to build such a range were themselves short of iron, the bottom of “normal” ends up too low.

Weyand made that argument to TODAY. “The recommendations changed because using reference ranges, which take a presumed healthy population and define ‘normal’ using a standard curve doesn’t work for a condition that affects so many people,” she said.

The CDC team tried a different approach, asking at what ferritin level the body starts to show strain. Using national survey data on 2,569 children and 7,498 women who were not pregnant, they looked for the point at which hemoglobin begins to fall and a second blood marker of iron shortage begins to rise. Both markers pointed to about 20 for children and about 25 for women, providing physiological evidence of potential new thresholds.

The society’s numbers sit close to those: 20 for young children, and 30 for adults.

Marshall described what the gap between old and new numbers has meant in a clinic. “It’s all too common right now that women are told, ‘Oh, your ferritin is 25, but our lab says that it’s not low until it’s less than 15,’” she told NBC.

How many people the iron deficiency thresholds affect

A cutoff of 30 takes in a large share of the population. Researchers at Brigham and Women’s Hospital applied it to a nationally representative survey of 8,021 US adults in 2017 to 2020. In that study absolute iron deficiency was defined as serum ferritin less than 30 ng/mL regardless of transferrin saturation, almost the same line the society has now drawn. An estimated 14% of adults in the US met the criteria for absolute iron deficiency.

Low ferritin was not confined to people who were anemic or seriously ill. Among adults without anemia, heart failure, chronic kidney disease or current pregnancy, the estimate was still 11%. A further 15% of adults had what the researchers call functional iron deficiency, with ferritin at 30 or above but low transferrin saturation.

Teenage girls and young women stand out. Almost 40% of teenage girls and young women have low levels of iron, according to a 2023 study published in JAMA that NBC cited. The society claims that the condition is widely overlooked, with up to 70% of cases missed among high-risk populations due to limited screening and variability in diagnostic reference ranges.

Specialists do not agree on whether iron deficiency is becoming more common or simply being noticed. Leo Buckley of UT Southwestern Medical Center, a co-author of the Brigham analysis, told NBC that newer work by his team shows a 3% increase in prevalence between 1999 and 2020. Andrew Eisenberger, who directs the classical hematology service at Columbia University Irving Medical Center, read the trend differently. “I actually don’t think that there’s more iron deficiency,” Eisenberger said. “I think we’re just kind of waking up.”

What treating low ferritin without anemia has been shown to do

A diagnosis is useful to the extent that acting on it helps. For iron deficiency with anemia, iron treatment is standard. For the people the new cutoffs add, those with low ferritin and normal hemoglobin, the trial evidence is narrower.

The fullest summary is a 2018 meta-analysis led from the University of Manitoba, which pooled 18 randomized trials enrolling 1,170 adults who were iron deficient without anemia. In those trials iron supplementation was associated with reduced self-reported fatigue, a result that came from four trials with 714 participants. It was not associated with differences in objective measures of physical capacity, such as peak oxygen uptake during exercise. Fatigue improved on questionnaires, in other words, and measured exercise performance did not.

The guideline does not address treatment. Additional ASH guidance on the treatment of iron deficiency is anticipated in 2027, the society said.

Nor does it settle who should be tested in the first place. On pregnancy, the US Preventive Services Task Force concluded in 2024 that the current evidence is insufficient to assess the balance of benefits and harms of screening for iron deficiency and iron deficiency anemia in pregnant persons. That statement concerned people with no symptoms. It was a verdict on the evidence, not a recommendation against testing.

What the ferritin guideline leaves open

The first open question is how accurate the test is at the new cutoffs. A Cochrane review, a type of systematic review produced to a strict protocol, examined 108 studies of ferritin testing in 2021. Its authors concluded that at a threshold of 30 micrograms/L, there is low-certainty evidence that blood ferritin concentration is reasonably sensitive and a very specific test for iron deficiency in people presenting for medical care.

The figures behind that sentence came from nine studies with 512 adult patients. At 30, ferritin identified 79% of people with confirmed iron deficiency and correctly cleared 98% of those without it. The plausible range around the first figure ran from 58% to 91%.

Those were patients who had come to a doctor. For people with no symptoms, the reviewers found there is insufficient evidence to know whether ferritin concentration performs similarly when screening asymptomatic people.

The second open question is outcomes. A guideline is a panel’s judgment of the evidence. This one drew on reviews of how common iron deficiency is and of studies that inform diagnostic cutoffs, which is different from following people diagnosed at one threshold or another to see how they fare. The guideline itself notes that gaps in the literature and research priorities were also identified.

Beyond those two questions, a low ferritin is a result that needs explaining. Iron stores fall for a reason, commonly blood loss, a diet low in iron or a gut that absorbs it poorly, and the cause matters as much as the number.

Iron is also not harmless in excess. TODAY’s report, written by a dietitian, cautioned that too much iron can be harmful and that treatment depends on whether a person has iron deficiency and what is causing it.

What changes for people with low ferritin

The practical effect depends on laboratories and health systems, which set the ranges printed on reports. Powers said the panel hopes that “health systems adopt these thresholds for diagnosis”. Until they do, a result of 25 may still arrive marked as normal.

The society’s own summary of the shift is that the recommended ferritin cutoff numbers for diagnosis are now higher across all populations, so some people once told their iron was adequate would now meet the definition of deficiency. What a particular ferritin result means depends on symptoms, other iron tests and the reason for any shortfall, which is assessed by a person’s doctor.

For women the line has moved from a long-used 15 to 30 on the judgment of an expert panel, and the trials of treating people without anemia have so far shown less fatigue on questionnaires and no measured gain in physical capacity.