New Guidelines Raise the Bar for Diagnosing Iron Deficiency

Iron deficiency is one of the most common health conditions in the world, affecting an estimated one in three people, or roughly 10 million adults in the U.S. and 2 billion people globally. Yet many go undiagnosed and untreated, sometimes living with symptoms for months or years before getting an answer. The American Society of Hematology (ASH) issued new evidence-based clinical practice guidelines aimed at closing that gap, addressing how iron deficiency is recognized across adults, young children, menstruating and pregnant individuals, and people with inflammation.

Iron deficiency occurs when the body’s iron stores drop too low to support normal hemoglobin production, the molecule responsible for carrying oxygen through the blood. Iron also supports brain function, the immune system, muscles, skin, hair and nails. Left untreated, iron deficiency can progress to iron deficiency anemia, the most common hematologic condition worldwide, which can lead to serious complications if it goes unaddressed.

Why so many cases slip through

ASH’s guidelines point to inconsistent testing practices and diagnostic thresholds as key reasons iron deficiency is so often missed, with up to 70% of cases in high-risk populations going undiagnosed. ASH President Robert S. Negrin, M.D., called iron deficiency and iron deficiency anemia “among the most common yet neglected medical conditions globally,” noting that patients frequently live with fatigue, weakness, dizziness or difficulty concentrating for extended periods before the condition is recognized.

New numbers for diagnosis

Iron deficiency is diagnosed through a blood test measuring ferritin, the protein that stores iron in the body. ASH’s new guidance raises the ferritin thresholds used to identify deficiency across several populations:

• Children ages 9 months to 4 years: 20 nanograms per milliliter (ng/mL) or lower
• Adults, and menstruating or pregnant individuals: 30 ng/mL or lower
• High-risk groups, including those with heavy menstrual bleeding or pregnant individuals with anemia: 50 ng/mL or lower
• Adults with inflammation, including those with cancer, inflammatory bowel disease or infectious disease: ferritin under 100 ng/mL, or transferrin saturation under 20%

Because these cutoffs are higher than previous standards, some people whose past test results were read as normal, particularly if their ferritin level was close to the old cutoff, may meet the new criteria for iron deficiency. Guideline chair Jacquelyn M. Powers, M.D., M.S., section chief of hematology at Texas Children’s Hospital and associate professor of pediatrics at Baylor College of Medicine, said the goal is to give both clinicians and patients clearer guidance in an area where consensus had been lacking, and to empower patients to ask for testing that reflects the updated standards.

What this means for patients

Anyone with symptoms such as fatigue, shortness of breath, rapid heartbeat, headache or pale skin, particularly those in higher-risk groups such as people who are pregnant or menstruating or managing gastrointestinal conditions or chronic disease, may want to talk with their doctor about ferritin testing under the new thresholds.

What comes next

The guidelines were developed by experts across medical specialties, with input from a patient who has experienced an iron deficiency diagnosis firsthand, and were published in ASH’s peer-reviewed journal, Blood Advances. Additional ASH guidance on treatment is expected in 2027, alongside the organization’s broader Iron Deficiency Blueprint, a strategic effort to reduce the global burden of iron deficiency and iron deficiency anemia.