Something I see again and again, both in practice and in the questions that come through to our team, is people receiving their iron results and not knowing what to make of them.

A ferritin of 45 becomes 53 after three months of supplementing and the immediate reaction is:

Is it even working?

It's a completely understandable question.

But it’s focusing on only one part of the picture and also ignoring how the person feels.

Iron studies are made up of several markers, each offering different information about how your body is using, transporting and storing iron. Each parameter contains its own information and the four tests together also communicate a picture. Both are useful.

Ferritin is your storage marker. It’s the best reflection we currently have of the iron available in your bone marrow where it’s crucial for the creation of red blood cells. It's also often the test result people pay the most attention to.

But I also pay close attention to transferrin, a protein responsible for transporting iron.

It tends to confuse people when they see a marker related to iron, elevated. It’s easy to think “I must have too much iron” yet when transferrin is high, or at the upper end of the normal range, it’s a sign your body is seeking more iron. Transferrin is not iron itself – it is a carrier of iron. It’s helpful to think of it as a bus.

So when transferrin is elevated (or high end normal), it’s a sign of "iron hunger" – the body is producing more buses in an attempt to pick up more passengers (iron). The normal range for adults for transferrin is 2 – 3.6 g/L however once transferrin hits about 2.6 g/L, it’s (typically) an indication that more iron is being requested.

Your body is effectively increasing its capacity to transport iron because it is seeking more of it. In many cases, this can provide valuable context, even when ferritin appears adequate on paper.

This is why it’s wise not to look at ferritin in isolation.

A slowly rising ferritin alongside other markers that suggest the body is actively working to acquire and utilise iron can tell a very different story from a ferritin number alone.

The body is constantly adapting, regulating and striving for homeostasis. The more we understand the language of our blood tests, the more clearly we can see what that process looks like.

Because the numbers themselves are only part of the story. Knowing how to interpret them is where the real insight lies.