New Iron Deficiency Guidelines Double Ferritin Cutoff, Meaning Many Told They Were 'Normal' May Not Be

WASHINGTON — Many Americans who were told their iron levels were normal may in fact be iron deficient under new diagnostic standards from the nation's leading blood disorder specialists, a change aimed at catching one of the world's most common and overlooked medical conditions earlier.

The American Society of Hematology, or ASH, has raised the blood-test thresholds doctors use to diagnose iron deficiency, roughly doubling the cutoff for most adults. The guidelines, issued Sept. 16 and published in the society's peer-reviewed journal Blood Advances, are the group's first evidence-based clinical practice guidelines on diagnosing the condition.

Iron deficiency affects about 2 billion people worldwide and about 10 million adults in the United States, according to ASH. Left untreated, it can progress to iron deficiency anemia, one of the most common types of anemia, which occurs when a lack of iron prevents the body from making enough hemoglobin, the molecule that carries oxygen through the body.

"Iron deficiency and iron deficiency anemia are among the most common yet neglected medical conditions globally," ASH President Dr. Robert S. Negrin said in a statement.

"Many patients live with symptoms such as fatigue, weakness, dizziness or difficulty concentrating for months or even years before iron deficiency is recognized. These guidelines are an important step toward closing that gap by helping clinicians diagnose iron deficiency earlier and more accurately, so more patients can receive the care they need," Negrin said.

What changed

Iron deficiency is diagnosed with a blood test that measures ferritin, a protein that stores iron and serves as a marker of the body's iron reserves.

Under the new standards, adults can be diagnosed with iron deficiency at a ferritin level of 30 nanograms per milliliter or lower, up from the previous threshold of 15. For children ages 9 months to 4 years, the threshold rises from 12 to 20 nanograms per milliliter.

The 30 nanogram threshold also applies to people who are menstruating or pregnant. For pregnancy specifically, the guidelines strongly recommend against using the older cutoff of 15.

For patients with symptoms or ongoing risk factors for iron deficiency, the guidelines say a threshold of 50 nanograms per milliliter or lower may be appropriate.

The guidelines apply whether or not a patient has anemia, a key shift intended to help doctors identify iron deficiency before it progresses.

The panel's chair said the updated thresholds offer "clear guidance in an area where consensus has been lacking."

Why the old numbers missed patients

Medical experts say older cutoffs were highly specific but missed many people with clinically meaningful iron deficiency.

Part of the problem lies in how normal ranges were set. Many ferritin reference ranges were drawn from "apparently healthy" populations that included people who were already iron deficient. Results can also vary by laboratory: a ferritin of 30 nanograms per milliliter can come back anywhere from 21 to 42 depending on where the test is run.

The guidelines recommend shifting away from a statistical reference range toward a clinical decision threshold. In practical terms, a patient whose ferritin level was previously flagged as normal, such as a reading of 24, would now meet the diagnostic criterion for iron deficiency.

ASH estimates that up to 70% of cases in high-risk groups go undiagnosed. People at higher risk include those with gastrointestinal problems, dietary restrictions, chronic health conditions, and women who are pregnant or menstruating.

The scale of the issue is significant. A U.S. analysis of national survey data from 2017 to 2020 using the 30 nanogram cutoff found absolute iron deficiency in 14% of adults and 34% of women younger than 50. The panel's reviews also put global prevalence at 30% among young children, 27% among menstruating individuals and 37% during pregnancy.

Inflammation complicates testing

The guidelines also address patients with inflammation, a group in whom ferritin results can be misleading. Because ferritin can rise with inflammation, it can mask an underlying deficiency.

For adults with anemia of inflammation, the panel suggests ordering ferritin and transferrin saturation, a measure of iron transport, together. Doctors should consider iron deficiency when transferrin saturation is below 20% or ferritin is below 100 nanograms per milliliter.

Common symptoms often overlooked

Symptoms of iron deficiency, including fatigue, weakness, dizziness, shortness of breath and difficulty concentrating, are often overlooked until the condition progresses to anemia.

Untreated iron deficiency anemia impairs oxygen transport in the body and can lead to life-threatening complications.

What patients should do

The new guidance means people who previously did not meet the criteria may now have ferritin levels low enough to be diagnosed. ASH recommends that people talk with their doctors about having their ferritin levels tested under the new criteria.

For primary care clinicians, the guidelines support evaluating iron deficiency independently of anemia and reconsidering past results that were categorized as normal but fall within the newly recommended ranges.

Experts caution against self-treatment. Doctors have warned that people should not take iron supplements without medical advice, as excess iron can cause its own health problems and symptoms like fatigue can have many causes.

Limits of the evidence

The panel acknowledged the evidence behind the change is thin and called for randomized trials comparing patient outcomes under different thresholds. The clinical benefit of moving the threshold from 15 to 30, or to 50 in some cases, has not been directly established through trials that diagnosed and treated patients using competing ferritin cutoffs.

The guidelines also focus only on diagnosis. Separate ASH guidance on treating iron deficiency is expected in 2027.

The recommendations were developed by experts across medical specialties, with input from a patient who had experienced an iron deficiency diagnosis firsthand. ASH said it is also developing an Iron Deficiency Blueprint, a strategic plan to help reduce the global burden of iron deficiency and iron deficiency anemia.

Note: The guideline chair's quote is attributed to "the panel's chair" because the source I found cut off her surname; if you can confirm the full name on ASH's press release, add it before publishing.