Ferritin levels and iron deficiency: What the new cutoff means

Key takeaways:

• The American Society of Hematology (ASH) now suggests diagnosing iron deficiency at a ferritin of 30 ng/mL or lower in most adults, including people who menstruate or are pregnant, up from the 15 ng/mL cutoff used before.
• A normal hemoglobin doesn't rule out low iron. Iron deficiency without anemia is nearly twice as common as iron deficiency with it, so a blood count alone can miss it.
• A cutoff of 50 ng/mL or lower may fit people with heavy or abnormal periods, symptoms, planned pregnancy, or pregnancy with anemia, and inflammation changes how ferritin is read.
• A low result is a reason to find out why your iron is low, since a supplement can raise the number without answering that. Chest pain or severe shortness of breath needs urgent care.

Ferritin is the protein that stores iron, and a ferritin test is the usual way to see how much you have in reserve. In September, ASH updated its evidence-based guidelines for diagnosing iron deficiency, and they moved the line. Here's what changed, who it touches, and what to do with a result you've already been given.

The American Society of Hematology’s new ferritin cutoff: 30 ng/mL, up from 15

ASH raised the ferritin cutoff for diagnosing iron deficiency in most adults from 15 to 30 nanograms per milliliter (ng/mL), and it advises against using 15 for people who are menstruating or pregnant. The cutoff applies whether or not you have anemia, which is the point: the goal is to catch low iron earlier.

ASH also set its own cutoff for children 9 months to 4 years old: 20 ng/mL or lower.

A ferritin at or below 30 that still reads as normal

Reference ranges differ from lab to lab, so the flag on your report may not line up with the new cutoff. ASH points to limited screening and variability in diagnostic reference ranges as reasons that up to 70% of cases may be missed in high-risk groups, including people who are pregnant or menstruating. A result you were told was normal under the old line is worth a second look under the new one.

Low iron with a normal blood count

Iron deficiency without anemia, meaning a normal hemoglobin with a low ferritin, is nearly twice as common as iron deficiency with anemia. Hemoglobin is the molecule in red blood cells that carries oxygen, and iron is what the body uses to build it. A complete blood count shows whether you're anemic. Ferritin shows how much iron you have set aside.

General Medicine clinician Poushali Bhattacharjee describes the two as answering different questions: one tells you how your red blood cells are doing today, the other tells you whether the reserve behind them is running low. That's why she looks at both together.

Identifying symptoms of iron deficiency

Tiredness, weakness, and shortness of breath are the most common, though mild iron deficiency can cause no symptoms at all. Feeling weak or tired more often than usual, or during exercise, is a typical pattern. ASH notes that many people live with fatigue, weakness, dizziness, or trouble concentrating for months or even years before iron deficiency is recognized.

Plenty of things cause fatigue, so a symptom alone doesn't point to iron. It does make a ferritin result worth reading with the full picture in front of you.

How inflammation changes the way ferritin is read

Ferritin also rises with inflammation, so in adults with inflammatory conditions, ASH suggests iron deficiency be considered when ferritin is under 100 ng/mL or transferrin saturation is under 20%. Transferrin saturation measures how much of your iron-carrying protein is actually loaded with iron. Only one of the two has to be low.

The inflammation can come from an infection or from a long-term condition such as cancer or inflammatory bowel disease. Dr. Bhattacharjee's rule is that a lab value read on its own tells you little. Your symptoms, your history, and what else is going on are the rest of the picture.

What a low ferritin should lead to, and when to be seen

A ferritin at or below the cutoff is a reason to find out why your iron is low, because a supplement can raise the number without explaining it. The usual reasons are blood loss, trouble absorbing iron, pregnancy, or heavy periods. In men and postmenopausal women, iron deficiency anemia is often the result of slow, hidden bleeding in the digestive tract, which is why the American Gastroenterological Association recommends a digestive tract evaluation, like a colonoscopy, for these individuals.

Talk with a clinician before starting iron on your own. Iron supplements can have side effects, ,too much iron can be harmful, and the right amount depends on your situation. Chest pain or severe shortness of breath needs urgent care or a call to 911, not a lab order.

If you want a place to start, the Iron Insight test checks ferritin along with other iron markers, and a complete blood count shows whether you're anemic. Getting both at the same time gives a clinician the full picture at once. After your results are in, a General Medicine clinician who won't be starting from zero can go through them with you and help work out the why, and General Medicine stays involved afterward so your story doesn't reset. Clinician review is booked separately from the tests, and you'll see the price before you decide.

Frequently asked questions

Do I need to get retested if my ferritin was between 15 and 30?

A result above 15 and at or below 30 that was called normal now sits at or below the new ASH cutoff. Whether to retest depends on when it was drawn and what has changed since, so bring the number and the date to a clinician.

Who is more likely to have low iron?

ASH lists people who are pregnant or menstruating, children, and people with digestive conditions, dietary restrictions, blood loss, or other chronic health conditions as higher risk.

Do other medical societies use a different ferritin cutoff?

They can. The American Gastroenterological Association, for example, suggests 45 ng/mL for diagnosing iron deficiency in people who have anemia. Cutoffs vary by population and purpose, which is one more reason a clinician reads your number against your whole picture.

Making sense of your ferritin result

ASH moved the ferritin line for most adults from 15 to 30; a normal blood count doesn't settle the question, and inflammation can change what a number means. A low result is the start of finding out why, and a clinician can help with that.