Ferritin check
Ferritin rises with inflammation. A normal-looking ferritin can therefore hide a real iron deficiency. This check corrects for that using your CRP.
Ferritin check
Ferritin check
Ferritin alone does not tell the whole story. Add your CRP for a more reliable verdict. Everything is calculated in your browser — your values are never stored or sent anywhere.
You did not enter a CRP. Without it we cannot see whether inflammation is pushing your ferritin up artificially — and that is exactly how iron deficiencies get missed.
Your transferrin saturation is below 20%. That can mean too little iron is actually available for making red blood cells, even if your stores look adequate on paper.
The WHO itself rates the certainty of these thresholds as low to very low: they descend from a 1993 expert consultation. Read your result as a direction, not a diagnosis.
This check follows the WHO 2020 guideline and is intended for education, not diagnosis. The WHO itself rates the certainty of these thresholds as low to very low, and reference ranges differ between laboratories. Always discuss your result with a doctor.
Why ferritin alone is not enough
Ferritin measures your iron stores, but it is also an inflammatory protein. With an infection, chronic inflammation or obesity it rises independently of your iron. A real deficiency can therefore hide behind a value that looks perfectly fine.
What CRP and transferrin saturation add
CRP shows whether inflammation is present. If it is, the WHO raises the iron-deficiency threshold from 15 to 70 µg/L. Transferrin saturation shows how much iron is actually available: below 20% is too little, above 45% possibly too much.
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Frequently asked questions
What is a normal ferritin level?
The WHO calls it an iron deficiency below 15 µg/L in adults. In practice anything below 30 µg/L is often treated as depleted stores. If inflammation is present (CRP above 5 mg/L), that threshold moves to 70 µg/L.
Why do I need to enter my CRP?
Because ferritin rises with inflammation. Without CRP you cannot tell whether a normal ferritin is genuinely normal or artificially inflated. That is precisely where iron deficiencies get missed.
What is transferrin saturation?
The percentage of your transport iron actually loaded with iron. We calculate it from your serum iron and your transferrin. Below 20% points to too little available iron, above 45% to possible iron overload.
My ferritin is high. Do I have too much iron?
Not necessarily. Raised ferritin far more often comes from inflammation, alcohol or fatty liver than from iron overload. Only when your transferrin saturation is also above 45% does overload become more likely.
Which blood test do I need for this?
Ferritin, CRP, serum iron and transferrin. They come together in the iron status test.
Want your iron status measured?
The iron status test measures your ferritin, serum iron, transferrin and your CRP — exactly the values this check needs.