New ASH guidelines raise the bar for diagnosing iron deficiency

The American Society of Hematology (ASH) has issued new clinical practice guidelines to improve the diagnosis of iron deficiency, a condition affecting billions worldwide that is routinely missed because of inconsistent testing practices and outdated diagnostic thresholds. The guidelines push for higher serum ferritin cutoffs across multiple at-risk populations — including children, pregnant individuals, and those with chronic conditions — to catch iron deficiency before it progresses to anemia.

A key concern driving the update: most physicians were trained to think about iron deficiency only in the context of anemia, but iron plays critical roles in immune function and brain health long before anemia sets in. Standard complete blood counts (CBCs) miss more than 80% of iron deficiency cases, and ferritin testing is not routinely included.

By the Numbers:

• 20 ng/mL — new threshold for children ages 9 months to 4 years (up from 12 ng/mL)
• 30 ng/mL — new threshold for adults and pregnant/menstruating individuals (up from 15 ng/mL)
• 50 ng/mL — recommended for high-risk groups (e.g., heavy menstrual bleeding, pregnant individuals with anemia)
• 100 ng/mL — threshold for those with active inflammation (e.g., IBD, cancer)
• ~14% of U.S. adults have absolute iron deficiency; another ~15% have functional iron deficiency

Why it matters: Iron deficiency is massively prevalent but chronically underdiagnosed. These updated thresholds give clinicians a clearer, more sensitive framework to identify at-risk patients earlier — potentially preventing serious complications and reducing the cycle of reactive treatment.