ASH 2026: New Ferritin Thresholds for Iron Deficiency

On 16 September 2026, the American Society of Hematology (ASH) published new guidelines for diagnosing iron deficiency in Blood Advances. The headline change is the ferritin cut-off itself: the thresholds labs and doctors use to call a result deficient are now higher than the ones most people grew up with. That means some results previously read as “ferritin is fine” now meet the new definition of iron deficiency. If you’ve ever been told your iron was normal at a ferritin of 20–25 ng/mL, it’s worth understanding exactly what changed — see our ferritin overview for how the marker itself works.

What Changed: Old vs New Thresholds

Until now, the reference point most clinicians used was the WHO threshold: ferritin below 15 ng/mL in adults and below 12 ng/mL in children signalled depleted iron stores. ASH 2026 raised these cut-offs.

ASH encourages laboratories to report these thresholds as clinical decision limits — more on what that means for your own lab report further down.

To be clear about the evidence: all of ASH’s threshold recommendations are conditional and based on low-certainty evidence (very low for the inflammation criterion), so they guide a doctor’s judgement rather than replace it.

In practice, this looks like: an adult with a ferritin of 22 ng/mL used to be reassured that their iron stores were fine, because the number sat above the old WHO threshold of 15 ng/mL. Under the ASH 2026 criterion, that same result now falls into the deficiency range, since the threshold for adolescents 11 and up and adults is now ≤ 30 ng/mL. For a child, the same logic applies with the new ≤ 20 ng/mL threshold in place of the earlier < 12 ng/mL: ASH’s press release lists that threshold for children aged 9 months to 4 years, while ASH’s implementation tool for laboratories applies the same ≤ 20 ng/mL decision limit to children up to 10 years. Which limit applies to a given child’s result is for their paediatrician to decide.

”50 ng/mL or Lower” Is a Clinical Remark, Not a New Norm

Separately, ASH added a remark — not a graded recommendation — for people with symptoms and/or risk factors for iron deficiency, including heavy menstrual bleeding, and for pregnant people with anaemia: a ferritin of 50 ng/mL or lower may be appropriate grounds to diagnose deficiency.

This is important to read correctly: 50 ng/mL is not a new normal threshold and not an “optimal level” to aim for. It’s a piece of clinical judgement for a specific situation — when symptoms or risk factors are present, a doctor may diagnose deficiency at a ferritin of 50 ng/mL or lower, rather than waiting for the value to drop to 30 ng/mL or below. Without symptoms or risk factors, this remark doesn’t apply.

When Inflammation Is Present: A Different Criterion

Ferritin becomes unreliable in the presence of active inflammation, acute or chronic. This covers infections, cancer, chronic kidney disease, heart failure, rheumatologic conditions, and other chronic inflammatory disorders. In these settings, inflammation itself pushes ferritin up — ferritin is an acute-phase protein, and inflammation can raise it enough to mask a true deficiency — so a formally “normal” number doesn’t rule out iron deficiency.

For this group, ASH 2026 defines iron deficiency by a different criterion: transferrin saturation (TSAT) below 20% OR ferritin below 100 ng/mL. Anaemia of inflammation is a diagnosis of exclusion.

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If you’re already tracking inflammation separately, it helps to review ferritin alongside CRP — that combination clarifies whether an elevated ferritin is explained by an inflammatory response or not. The practical difficulty is that ferritin in someone with chronic inflammation can look “normal” or even elevated while true iron stores are already depleted — so in this group a “normal-looking” ferritin doesn’t rule out deficiency. Either criterion is enough: ferritin below 100 ng/mL, or TSAT below 20% — which is why TSAT is worth measuring when ferritin is 100 ng/mL or higher.

Don’t Wait for Anaemia to Suspect Deficiency

One of the core ideas in the new guideline is not to rely on the complete blood count alone. A CBC by itself isn’t adequate to identify iron deficiency: a normal haemoglobin doesn’t exclude it. Iron stores (ferritin) become depleted well before haemoglobin drops or red cell indices change — so ferritin, not a wait-and-see approach to anaemia, is the marker to act on.

Symptoms worth flagging to a doctor are non-specific and easy to write off as stress or overwork: fatigue, reduced exercise tolerance, restless legs syndrome, pica (an urge to chew ice or non-food items), and hair loss. None of these is diagnostic on its own, but combined with a low ferritin they support the clinical picture of deficiency.

For people who menstruate, ASH specifically calls out the value of a detailed menstrual history: it’s worth establishing whether heavy menstrual bleeding is present, since it’s a common underlying cause of iron deficiency and, if found, should be addressed. For the fuller picture, ferritin is traditionally assessed alongside a complete blood count and within a broader anaemia work-up, and persistent unexplained fatigue is one of the most common reasons people get ferritin checked for the first time.

Fatigue or reduced exercise tolerance often show up at the still “pre-anaemic” stage, while haemoglobin is normal — which is exactly why it’s worth testing ferritin on its own, rather than waiting for the CBC to move.

How to Prepare for the Test

Ferritin itself doesn’t need special preparation. But if serum iron and transferrin saturation (TSAT) are drawn alongside it, give blood fasting and without taking iron supplements or multivitamins beforehand — recent iron intake can distort the TSAT result.

It’s also worth avoiding testing during an acute illness: inflammation artificially raises ferritin, and the result may not reflect your real iron stores. If you’re planning to check ferritin during pregnancy, note that the new ≤ 30 ng/mL threshold applies to pregnant people too — for more on preparing for tests during pregnancy, see the article on pregnancy blood tests.

Your Lab Says “Normal”, but Your Result Meets the New Threshold

This is a real and common situation: ASH encourages laboratories to report these thresholds as clinical decision limits, but a lab’s reference range is a different thing — so a report may still flag a result such as 25 ng/mL as “normal” against the lab’s own reference range, even though it already meets the ASH 2026 definition of deficiency in adults.

If your result is formally “normal” but you can see it’s 30 ng/mL or below (or 20 ng/mL or below for a child), don’t start taking iron on your own. Discuss the result with your doctor — the cause needs to be established (diet, menstrual losses, a gastrointestinal source) before treatment is prescribed. Self-treating with iron supplements without a confirmed deficiency and a clear cause can mask a more serious problem.

A gap between the lab report and the clinical threshold isn’t a reason to doubt the test itself — it’s a reason to clarify which scale it’s being read against. If you’re unsure, the simplest approach is to bring the result to your doctor along with a note that the ASH 2026 thresholds differ from the lab’s classic reference range, and decide together whether further investigation is warranted.

This kind of gap isn’t unique to ferritin: the lower limit of the reference range already varies between laboratories because of differences in methodology and reagents — and now there’s also a separate ASH 2026 clinical threshold on top, which may not match either of them.

How HealthLab Helps You Track Ferritin

A single ferritin number rarely tells the whole story — what matters more is how it moves over time: whether iron stores recover after treatment, or dip again later. HealthLab automatically recognises ferritin and other biomarkers from PDF lab reports issued by any laboratory and builds a trend chart over time. The band on the chart shows a reference range — the same kind printed on a lab report — not the ASH 2026 clinical decision limit, so it’s worth reading your trend together with a doctor in light of the new guideline. For more on reading that band and the trend line, see how to read a biomarker trend chart.

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