New Ferritin Cutoffs Could Help Identify Iron Deficiency Earlier

Updated ferritin thresholds from the American Society of Hematology (ASH) could help clinicians identify iron deficiency before it progresses to anemia. The change matters because iron stores can be low even when a routine blood count looks reassuring, and symptoms may appear before anemia develops.

Recent estimates suggest as many as one in three Americans have iron deficiency or iron deficiency anemia, though many may not know it. In a statement, ASH President Robert S. Negrin, M.D., described both conditions as common and often overlooked, with some people experiencing fatigue, weakness, dizziness or trouble concentrating for months or years before diagnosis.

The new guidance sets ferritin cutoffs for different groups. Ferritin is a protein that gives clinicians a useful estimate of the body’s iron stores. The thresholds are intended to make results more consistent and help flag deficiency that older reference ranges could miss. They’re guidance for diagnosis, not a substitute for interpreting a person’s results in context.

How low iron affects the body

Iron helps the body make hemoglobin, a protein in red blood cells that carries oxygen to tissues. Iron deficiency means the body’s stores are too low. If the shortage becomes severe enough to reduce red blood cells or hemoglobin, it can lead to iron deficiency anemia.

Low iron can develop when someone doesn’t get enough from food, doesn’t absorb it well, loses it faster than it can be replaced, or has higher needs. Anemia is one consequence, but it isn’t the only reason iron matters. Iron also supports other functions, including the production of neurotransmitters and oxygen delivery through myoglobin, a protein found in muscle.

That helps explain why fatigue, difficulty concentrating and shortness of breath may occur before anemia is apparent. Some people have no noticeable symptoms at first. When anemia develops, symptoms can become more pronounced and may include pale or yellowish skin, weakness, a rapid heartbeat, headache, lightheadedness, cold intolerance or poor sleep. Other possible signs include chest pain, a pounding or whooshing sound in the ears, cravings for ice or clay, a sore or smooth tongue, brittle nails, hair loss and restless legs.

These symptoms can have many causes. Their presence alone doesn’t confirm iron deficiency, and a clinician can assess them alongside blood tests and a person’s health history.

What the updated thresholds change

Ferritin testing can reveal depleted iron stores, but it may not be included in routine screening. Hemoglobin tests, for example, can help identify anemia but don’t show the full picture of iron stores. Kelsey Martin, M.D., a hematologist at Yale Medicine, has noted that some people may have iron deficiency symptoms before anemia appears.

Until now, clinicians lacked evidence-based ferritin thresholds for the general population, according to Angela Weyand, M.D., a member of the ASH panel that developed the new guidance. Older approaches often compared a person’s ferritin result with reference data from the general population. Results at the lowest 2.5% were considered abnormal, even though iron deficiency may affect a much larger share of people. Reference ranges also varied among laboratories.

The ASH guidance proposes these ferritin thresholds:

• Children from 9 months to 4 years: 20 ng/mL
• Adults: 30 ng/mL
• Higher-risk groups, including pregnant people with anemia and people with heavy menstrual bleeding: 50 ng/mL
• Adults with inflammation, such as people with cancer, inflammatory bowel disease or an infectious disease: 100 ng/mL, or transferrin saturation below 20%

A ferritin result below the threshold for a person’s group indicates iron deficiency under these recommendations. Clinicians may consider other test results and the broader clinical picture when deciding what a result means.

Inflammation affects how ferritin is interpreted. Ferritin can rise in response to infection, inflammation or other stress on the body, even when iron stores are low. For that reason, the guidance uses a higher ferritin threshold for people with inflammation and includes transferrin saturation, another measure of iron availability, as an alternative indicator.

Why early recognition matters

Earlier identification may help clinicians address low iron before anemia develops and look for the reason stores have fallen. Possible causes include limited intake, problems absorbing iron, increased need, heavy menstrual bleeding or blood loss from the digestive tract. Conditions such as celiac disease and inflammatory bowel disease can affect absorption or contribute to blood loss, so an iron deficiency finding can prompt further evaluation.

Treatment generally involves replacing iron with oral or intravenous medication. When a health condition is contributing to the deficiency, care may also address that cause. The appropriate approach depends on the person and their circumstances; these guidelines don’t establish a treatment plan for everyone with a low result.

For people with ongoing fatigue, weakness or other symptoms, it may be useful to ask a doctor whether ferritin testing fits their situation. A clinician or pharmacist can also discuss questions about treatment and possible side effects. The key change is that ferritin results may now be assessed against thresholds designed to catch low iron sooner, while inflammation and possible underlying causes still need careful interpretation.