Ferritin, haemoglobin, transferrin saturation, what they mean and what to look for.
Getting a print-out that says your iron test is normal can be more confusing than helpful if nobody explains what was actually measured. Iron status isn’t captured by a single number; it’s a picture built from several different markers, each telling you something different.
Ferritin reflects your body’s stored iron reserves. It’s usually the most sensitive early marker of iron deficiency; levels can fall well before anaemia develops. However, ferritin can also rise in response to inflammation or infection, which can mask a true deficiency, so it needs interpreting alongside how you’re feeling.
Haemoglobin measures the oxygen-carrying protein in your red blood cells. This is what defines anaemia when it falls below the normal range, but by the time haemoglobin drops, iron stores have often already been low for some time.
Transferrin saturation shows what percentage of the protein that transports iron around your bloodstream is actually carrying iron. A low percentage suggests your body doesn’t have enough iron to go around, even if other markers look borderline.
Laboratory reference ranges are built from population averages, not from what makes an individual feel well. A ferritin of 15 sits within many labs’ technically normal range, yet UK clinical guidance generally treats ferritin below 30 µg/L as showing iron depletion, and many women only start feeling genuinely better once ferritin rises well above that.
Results should always be read in context: your symptoms, your history, and the trend over time matter as much as where a single number sits within a reference range.