What the research found

The American Society of Hematology has updated its diagnostic guidelines for iron deficiency, recommending a ferritin threshold of 30 ng/mL or lower to identify deficiency in most adults — double the World Health Organization's previous cutoff of 15. This change reflects evidence that the lower threshold was missing more than half of people with depleted iron stores. The new guidance acknowledges that in certain clinical contexts (heavy periods, planned pregnancy, upcoming surgery, or known risk factors), doctors may apply an even higher threshold of 50 to catch cases earlier.

Iron deficiency and iron deficiency anaemia exist on a spectrum. Your body prioritises maintaining normal haemoglobin and red blood cell counts by drawing down iron reserves first, meaning blood tests can appear normal in early-stage deficiency. Ferritin — which reflects stored iron — is the most useful single marker for assessing total body iron status, though it can be artificially elevated during inflammation or infection.

Why it matters for you

If you're tracking biomarkers on MyKine, ferritin is worth monitoring alongside your haemoglobin. Fatigue, poor concentration, irritability and restless legs are among the symptoms that can arise when iron stores deplete, yet many people with low iron report no symptoms at all. This makes testing the only reliable way to identify the problem. The revised thresholds mean your result may now be interpreted differently depending on your clinical context — if you have heavy periods, are planning pregnancy, or have a known gut condition affecting absorption, your doctor may flag a ferritin of 30–50 as requiring intervention rather than dismissing it as normal.

Since your body cannot manufacture iron and can only recycle it efficiently from food, any shortfall accumulates slowly and takes time to reverse. Supplementation is typically faster than dietary measures alone, but identifying the underlying cause — whether it's menstrual loss, malabsorption, or occult bleeding — matters as much as treatment itself.

Caveats

• This is a clinical guideline update, not new primary research; the evidence base is observational and drawn from existing studies
• Ferritin is an indirect marker and can be misleading in the presence of inflammation or infection
• The new thresholds are primarily for North American practice; UK guidance already aligned with the 30 cutoff, and international standards may differ
• No data presented on the prevalence of symptoms or optimal treatment timelines in asymptomatic individuals