More people in the United States are low in iron than any other micronutrient, according to the American Society of Hematology (ASH). A 2024 study estimates that nearly one‑third of U.S. adults may be iron deficient, yet routine screening of children and pregnant people—groups at high risk—can miss more than 70% of cases. In response, ASH issued new diagnostic recommendations in September that raise ferritin thresholds and aim to catch deficiency earlier, even when anemia has not yet developed.
Understanding Iron Deficiency vs. Anemia
Anemia occurs when the body lacks enough red blood cells to transport oxygen, producing symptoms such as fatigue, dizziness, shortness of breath, heart palpitations, cold extremities, pale skin, brittle nails or hair loss. Iron deficiency is a common cause of anemia because iron is essential for producing hemoglobin, the oxygen‑carrying molecule in red blood cells. Ferritin, a protein that stores iron, supplies the element for new hemoglobin production. When ferritin levels fall, the body may be unable to generate sufficient red blood cells, leading to anemia.
Importantly, iron deficiency can generate many of the same symptoms without lowering hemoglobin or red blood cell counts. Dr. Ariela Marshall, associate professor of medicine at the University of Minnesota, emphasizes that “it is a common misperception that iron deficiency without anemia can’t cause symptoms, and one that we definitely need to correct.” Additional signs include restless‑leg syndrome and pica—cravings for non‑food items such as ice or clay—though the exact mechanism remains unclear.
Standard complete‑blood‑count tests count red blood cells but do not reveal iron stores, so they can miss early deficiency. Dr. Jacquelyn Powers, section chief of hematology at Texas Children’s Hospital and lead author of the 2026 guidelines, notes that “the symptoms of iron deficiency can be very subtle, or they can be attributed to many different things…Providers are not always thinking, ‘Oh, I need to check iron labs.’”
New Guidelines for Testing and Treatment
Blood iron concentration fluctuates with recent meals and therefore is not reliable for diagnosing deficiency. Ferritin testing remains the gold standard, but until now there was no universally accepted cutoff. The World Health Organization recommends a ferritin level below 15 ng/mL for school‑age children and adults, a threshold some researchers argue is too low and may miss many individuals with insufficient stores.
The updated ASH guidelines propose higher cutoffs: ferritin ≤20 ng/mL for children, ≤30 ng/mL for most adults, ≤50 ng/mL for adults with heavy menstrual bleeding, vegan diets, or long‑term antacid use, and ≤100 ng/mL for adults with inflammatory conditions. For the latter group, the guidelines also suggest measuring transferrin saturation to improve diagnostic accuracy.
These thresholds are intended to prompt testing even when patients are not anemic. Powers explains, “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.”
People who should consider ferritin testing include those experiencing persistent fatigue, brain fog, pale complexion, hair loss, dry skin, or cravings for ice. Social media posts have popularized the term “ferritin face” to describe a perceived visual pattern of iron deficiency, but both Powers and Marshall caution that a selfie cannot replace laboratory evaluation.
Underlying causes of deficiency in the United States often involve blood loss—particularly heavy menstrual periods in women—or chronic gastrointestinal conditions such as irritable bowel syndrome, celiac disease, or early‑stage colon cancer that impair absorption. Pregnancy, rapid growth in children, and the higher iron demands of endurance athletes also increase risk. While restrictive diets can contribute, Marshall notes they are not the primary driver for most Americans.
When deficiency is confirmed, oral iron supplements typically improve symptoms within weeks to months. Marshall advises that patients work with their physicians to identify the root cause of low iron, rather than relying solely on supplementation. “If that course of action helps, it means low iron was contributing to your health problems,” she says.
Overall, the new ASH recommendations aim to reduce the large proportion of missed iron deficiency cases by setting clearer ferritin thresholds, encouraging broader testing, and emphasizing that treatment can alleviate a wide spectrum of subtle yet impactful symptoms.
Mitchell Landsberg is a Senior Technology Correspondent at News Raise. He covers consumer electronics, artificial intelligence, software developments, and digital privacy trends.
