Understanding Your Iron Results

Being told your "iron is low" can be confusing because there isn't actually one single blood test that tells us everything about your iron status.

An iron study contains several markers. Some tell us how much iron you have stored, some tell us how much is circulating and available for use, and others help us understand whether low iron has started to affect your red blood cells.

This is why we need to look at the pattern of results, rather than one number in isolation.

You can have low iron stores without being anaemic, and you can also have a normal or even high ferritin result while iron availability is reduced. 

Why does iron matter?

Iron is needed to make haemoglobin, which allows red blood cells to carry oxygen around your body. It also plays an important role in energy production, brain and muscle function and immune health. 

When iron becomes too low, you may experience symptoms such as:

• Fatigue or low energy
• Weakness
• Reduced exercise capacity
• Shortness of breath
• Poor concentration
• Restless legs

Importantly, these symptoms can occur before you become anaemic.

What do the different iron markers mean?

Serum iron - what's circulating today

Serum iron measures the iron circulating in your blood at the time of the test.

Think of it as the iron currently in transit.

It can change depending on recent food intake, supplements, time of day, illness and inflammation. This means a single low serum iron result does not necessarily mean your iron stores are low. 

The takeaway: Never interpret serum iron by itself.

Ferritin - your iron storage tank

Ferritin is one of the most useful markers because it gives us an indication of how much iron your body has stored.

Think of ferritin as your iron storage tank.

When ferritin is low, your iron reserves are becoming depleted. This can happen well before haemoglobin falls. 

So:

Low ferritin + normal haemoglobin can still mean iron deficiency.

There is one important catch. Ferritin can also rise during inflammation, infection and with some liver conditions. So a normal or high ferritin doesn't always mean there is plenty of usable iron available. 

Transferrin and TIBC - your iron transport system

Transferrin is the protein that carries iron through your bloodstream.

A simple way to think about it is:

Iron = passengers
Transferrin = transport vehicles

When iron stores become depleted, the body may produce more transferrin to try to capture the limited iron available. This is why transferrin and TIBC are often higher in iron deficiency. 

Transferrin saturation - how full are the vehicles?

Transferrin saturation, or TSAT, tells us how much of your available iron transport capacity is actually being used.

A low TSAT means there is relatively little iron available to your tissues.

Importantly, this can occur because your iron stores are genuinely depleted or because inflammation is making stored iron less available. 

Haemoglobin - have you become anaemic?

Haemoglobin is the protein in red blood cells that carries oxygen.

A low haemoglobin means anaemia is present, but it doesn't tell us why.

Iron deficiency is one possible cause, but B12 or folate deficiency, blood loss, kidney disease, inflammation and other conditions can also cause anaemia. 

This distinction is important:

You can be iron deficient without being anaemic.

Putting your results together

These are simplified patterns rather than diagnostic rules. The original article outlines the same distinction between depleted stores, iron-deficiency anaemia, inflammation-related iron restriction and possible iron overload. 

What if ferritin is high?

High ferritin does not automatically mean you have too much iron.

Ferritin can increase with inflammation, infection and liver disease. However, genuinely excessive iron stores are also possible.

High ferritin together with high transferrin saturation is therefore a different picture from high ferritin with low serum iron and low transferrin saturation. 

Persistently abnormal results should be discussed with your doctor.

If your iron is low, ask why

Rather than immediately reaching for an iron supplement, the first question should be:

Why is my iron low?

Common reasons include:

• Not getting enough iron from food
• Heavy menstrual bleeding
• Other blood loss
• Pregnancy or increased requirements
• Poor absorption
• Coeliac disease or inflammatory bowel disease
• Previous gastrointestinal surgery
• Frequent blood donation

Repeated iron deficiency deserves investigation rather than simply replacing the iron over and over again. 

Should you take an iron supplement?

If your iron stores are genuinely depleted, increasing dietary iron and/or taking an iron supplement may be appropriate.

But more iron isn't always better.

Someone losing iron through heavy periods has a different issue from someone who isn't absorbing iron properly, or someone whose iron availability is being affected by inflammation. The appropriate treatment therefore depends on the underlying cause. 

Supporting iron through food

Haem iron, found in foods such as red meat, is generally more readily absorbed.

Plant foods including legumes, tofu, nuts, seeds, wholegrains and leafy greens provide non-haem iron.

Having vitamin C with plant-based iron can improve absorption, while tea and coffee consumed around an iron-rich meal can reduce absorption. 

The key message

Don't think of "iron" as one number.

Ferritin = storage
Serum iron = what's circulating now
Transferrin/TIBC = transport capacity
TSAT = how much iron is actually available
Haemoglobin = whether anaemia has developed

Your results make much more sense when these markers are considered together, alongside your symptoms, diet, blood loss, inflammation, gut health and medical history. 

So if something is high or low, don't just treat the number.

Ask why.

This information is for general education only and is not intended to diagnose or treat an individual medical condition. Abnormal or persistent results should be discussed with your GP or appropriately qualified healthcare practitioner.

To measure your blood levels of iron, you may wish to consider this NUTRIENT PROFILE blood pathology test, or our general RX METABOLIC MARKER profile.