Iron studies
Also known as: iron panel, iron blood tests, serum iron and TIBC, transferrin saturation test
A group of blood tests that together describe how much iron the body has stored, how much is circulating and how much of the transport protein transferrin is carrying it. Ferritin reflects the stores, serum iron and transferrin saturation the supply in transit, and the pattern across them separates iron deficiency from the anaemia of chronic disease and from iron overload.
- Kind
- Test panel
- Categories
- Vitamins, minerals & nutrition, Blood & haematology
- Specimen
- Serum
- Method
- Chemistry analyser, Immunoassay, Calculation from other results
- Type
- Blood test (panel)
- Sample
- Blood from a vein, ideally in the morning
- Used for
- Investigating anaemia and iron deficiency, suspected iron overload, monitoring iron treatment
- Measures
- Ferritin, serum iron, total iron-binding capacity and transferrin saturation
- Result
- Numeric panel read as a pattern
Why is it used?
- Anaemia, especially with small red cells (a low MCV)
- Tiredness, restless legs, hair loss or brittle nails when iron deficiency is suspected
- Suspected iron overload or haemochromatosis
- Monitoring iron treatment or blood transfusions
- Assessing iron status in kidney disease, heart failure and before surgery
What does it measure?
| Component | What it measures | A higher value may be seen in | A lower value may be seen in |
|---|---|---|---|
| Ferritin | The storage form of iron; the single most useful marker of iron deficiency | Iron overload, inflammation, infection, liver disease, some cancers | Iron deficiency |
| Serum iron | Iron circulating bound to transferrin at the moment of the sample | Iron overload, recent iron tablets, haemolysis | Iron deficiency, inflammation, chronic disease; varies through the day |
| Total iron-binding capacity TIBC | How much iron the blood's transferrin could carry, an indirect measure of transferrin | Iron deficiency (the body makes more transferrin), pregnancy, oestrogen | Inflammation, malnutrition, liver disease, iron overload |
| Transferrin saturation TSAT | The percentage of transferrin's iron-binding sites occupied, calculated from serum iron and TIBC | Iron overload including haemochromatosis | Iron deficiency, inflammation |
A high or low value can be associated with several different situations; the result is interpreted with other results, symptoms, history and clinical findings.
How is it performed?
A venous blood sample, ideally in the morning because serum iron varies through the day.
Specimen. Venous blood (serum), morning sample preferred
Do I need to prepare?
Fasting is sometimes requested. Iron tablets taken in the previous 24 hours raise the serum iron, so the laboratory may ask for them to be paused; say if you have had an iron infusion or transfusion recently.
What do the results generally mean?
| Finding | What it may indicate |
|---|---|
| Low ferritin | Iron deficiency; the cause (blood loss, poor intake or absorption, pregnancy) is then looked for |
| Low serum iron and transferrin saturation with normal or high ferritin | Usually the anaemia of inflammation or chronic disease, in which iron is present but locked away; ferritin alone can mislead here |
| High transferrin saturation and high ferritin | Possible iron overload; genetic testing for haemochromatosis may follow |
| Normal iron studies with anaemia | Iron is not the explanation; B12, folate, kidney function, thalassaemia and other causes are considered |
What can affect the result?
- Inflammation, infection and liver disease, which raise ferritin whatever the iron stores
- Time of day and recent meals or iron tablets, which change serum iron
- Pregnancy and oestrogen-containing medicines, which raise transferrin
- Recent transfusion or intravenous iron
Medicines. Oral and intravenous iron raise the results; proton-pump inhibitors reduce iron absorption over time; oestrogens raise transferrin.
What can the test not tell you?
- The cause of iron deficiency: bleeding from the gut, heavy periods, diet and malabsorption need their own investigation
- Whether anaemia is present, which is a haemoglobin question
- Iron status with certainty during active inflammation, when ferritin is unreliable
No single component is definitive: ferritin rises with inflammation, serum iron swings through the day and with meals, and the pattern across the panel is what the clinician reads. Soluble transferrin receptor is used in some laboratories to separate iron deficiency from inflammation.
Other tests commonly used with it
Catalogued concepts this page covers
Concepts of the master test taxonomy that resolve to this page; each links to its category.