Biomarker Glossary

Iron

Serum iron is the amount of iron circulating in your blood, bound to the transport protein transferrin. A serum iron test is interpreted alongside ferritin (iron stores), transferrin and transferrin saturation to give a full picture of iron status in the body.

Also known as: Serum Iron, Fe

Iron is most informative when read alongside related markers like Ferritin and Haemoglobin. A single number rarely tells the whole story. If your reading sits outside the typical range, share the full report with your GP or healthcare professional before drawing conclusions.

What is Iron?

Iron is essential for haemoglobin (the oxygen carrying molecule in red blood cells), muscle function, energy production and immune health. The body tightly regulates iron because both deficiency and excess cause problems.

A standard iron panel measures serum iron (iron in transit), transferrin (the iron transport protein), total iron binding capacity (TIBC, how much iron transferrin could carry), and transferrin saturation (how full the transport protein is right now, as a percentage).

Ferritin (iron storage) is the best single marker of iron status, but a full iron panel gives a richer picture, especially when interpreting borderline ferritin or investigating iron overload.

Why test Iron?

  • To investigate symptoms of fatigue, hair loss, breathlessness or low mood.
  • To distinguish iron deficiency anaemia from anaemia of chronic disease.
  • To screen for haemochromatosis (genetic iron overload), particularly with a family history.
  • To monitor iron supplementation.
  • When ferritin is borderline or affected by inflammation.
To investigate symptoms of fatigue, hair loss, breathlessness or low mood.

Iron normal range (UK)

Result What it means
Serum iron: 10 to 30 micromol/L Normal
Transferrin: 2.0 to 3.6 g/L Normal
TIBC: 45 to 80 micromol/L Normal
Transferrin saturation: 20 to 50% Normal
Transferrin saturation below 16% Iron deficient
Transferrin saturation above 50% Possible iron overload, particularly if above 45% in women or 50% in men consistently

Reference ranges vary slightly between laboratories. Always interpret iron panel results together, not individually. Ferritin is the most useful single marker.

About these ranges. The ranges above are typical UK clinical lab ranges aligned to NHS and Royal College of Pathologists guidance. Your Chxhealth report will show the specific reference range used by our partner lab, Randox, for each marker. Lab ranges vary slightly between providers and assays. Always interpret your results in the context of the range printed on your own report.

What causes high Iron?

  • Haemochromatosis (genetic iron overload)
  • Excess iron supplementation
  • Frequent blood transfusions
  • Liver disease
  • Recent iron rich meal or supplement (transient rise)
  • Some forms of anaemia (haemolytic, sideroblastic)

What causes low Iron?

  • Iron deficiency from insufficient dietary intake
  • Heavy menstrual bleeding
  • Pregnancy (increased demand)
  • Gastrointestinal bleeding
  • Coeliac disease and other malabsorption conditions
  • Chronic inflammation (anaemia of chronic disease)
  • Frequent blood donation
  • Endurance exercise

Symptoms of high Iron

  • Often no symptoms in early stages.
  • Joint pain (particularly knuckles)
  • Fatigue and weakness
  • Abdominal pain
  • Loss of libido or erectile dysfunction
  • Bronze or grey skin tone in severe cases
  • Diabetes, liver disease and heart problems if untreated

Symptoms of low Iron

  • Fatigue and weakness
  • Breathlessness on exertion
  • Pale skin
  • Hair shedding or thinning
  • Brittle nails
  • Restless legs
  • Reduced exercise tolerance
  • Difficulty concentrating, brain fog

How is Iron tested?

A full iron panel is measured from a blood sample. Morning testing (before any iron supplement or iron rich meal) gives the most accurate result.

Best tested alongside ferritin and ideally CRP (to rule out inflammation skewing the results).

Avoid iron supplements for 24 hours before testing for an accurate baseline.

Chxhealth samples are analysed by Randox, a UK laboratory accredited by UKAS. Results return in 3 to 5 working days.

How to support healthy Iron levels

  • Eat iron rich foods: red meat, liver, oily fish, eggs, lentils, beans, dark leafy greens, fortified cereals.
  • Pair plant iron sources with vitamin C foods (peppers, citrus, broccoli) to boost absorption.
  • Avoid tea, coffee and high calcium foods within an hour of iron rich meals.
  • If supplementing, take iron on an empty stomach with vitamin C. Every other day dosing may be better tolerated and absorbed than daily dosing.
  • Address heavy menstrual bleeding or gut symptoms that may underlie deficiency.

These are general lifestyle suggestions. Chxhealth is an information service. For personal medical advice, please speak to a healthcare professional.

Chxhealth panels that test Iron

16 Chxhealth biomarker panels include Iron. Each is analysed by Randox, a UK laboratory accredited by UKAS. Reports are delivered in 3 to 5 working days.

Iron FAQs

What is transferrin saturation?

The percentage of transferrin (iron transport protein) carrying iron at the moment of the test. Healthy adults are typically 20 to 50 percent saturated. Below 16 percent suggests iron deficiency. Above 45 to 50 percent suggests iron overload.

Should I test ferritin or full iron panel?

If you only test one marker, ferritin is the best single indicator. A full iron panel adds value when ferritin is borderline, when inflammation may be masking deficiency, or when investigating iron overload.

Why is my serum iron normal but ferritin low?

Serum iron reflects iron in transit (recent intake). Ferritin reflects long term stored iron. Stores deplete first, so ferritin drops before serum iron. This is why ferritin is the earlier and more sensitive marker.

What is haemochromatosis?

A genetic condition causing the body to absorb too much iron, which builds up in organs and causes damage over time. The C282Y mutation in the HFE gene is the most common UK cause. Affected people benefit from regular blood removal (venesection).

Can I get iron overload from supplements?

Yes, particularly if you take high dose iron without testing first. Always confirm deficiency with a blood test before supplementing iron.

Often tested with Iron

The biomarkers below are commonly investigated alongside Iron because they reveal connected aspects of the same physiological picture:

  • Ferritin: Ferritin shows stores, iron shows circulating supply.
  • Haemoglobin: Anaemia is confirmed via red cell markers.
  • Vitamin B12: Other classic deficiency contributing to anaemia.

Choose the right test for your goal

If you are reading about Iron because of a specific health goal, our buying guides walk you through which Chxhealth panels fit:

Sources and further reading

This page is informed by guidance from the NHS, NICE, Royal College of Pathologists and other UK authoritative bodies. For deeper detail or to verify the information, see:

About this page. Last reviewed: 13 May 2026. Next scheduled review: May 2027. This page has not yet been independently reviewed by a clinician. It is written from authoritative UK medical guidance (NHS, NICE, Royal College of Pathologists, peer-reviewed sources) but has not undergone formal clinical sign off.

Important. Chxhealth is a UK information service. We do not diagnose, treat or prescribe. The reference ranges and information on this page are general educational content and should not be used as a substitute for advice from a qualified healthcare professional. For any concerns about your health or results, please speak to your GP or another healthcare professional.