Iron studies
Iron blood test
A serum iron blood test measures the amount of iron circulating in your blood at the moment the sample is taken. On its own it swings with your recent meals and the time of day, so it's most useful as part of iron studies, read together with ferritin, transferrin and transferrin saturation.
- What it measures
- Iron circulating in your blood right now (serum iron)
- Sample
- Venous blood sample
- Fasting
- Preferred (a morning sample is best)
- Also known as
- serum iron
- Included in 57 Health tests
- 6 panels, from £95
Iron reference range
Guide only| Category | Guide range |
|---|---|
| Men (adult) | 11–30 µmol/L |
| Women (adult) | 7–27 µmol/L |
Serum iron varies through the day (usually higher in the morning) and rises after iron-rich food or supplements, so it can be misleading alone. It is interpreted alongside ferritin (stored iron), transferrin and transferrin saturation.
These are general UK adult guide ranges from public health sources, shown for orientation only. Reference ranges vary by laboratory, assay, age and sex, so your result is always interpreted against the range quoted by the analysing laboratory on your report.
What does a high iron level mean?
A high serum iron can simply follow a recent iron-rich meal or a supplement, but persistently high levels, especially with a high transferrin saturation, can point to iron overload, such as haemochromatosis.
Because a single reading is easily influenced by diet and timing, it is confirmed alongside ferritin and transferrin saturation before any conclusion is drawn.
What does a low iron level mean?
A low serum iron is often seen in iron deficiency, but it also drops during infection or inflammation without stores being low, so it can mislead on its own.
Ferritin is the more reliable marker of iron stores, which is why low iron is interpreted alongside ferritin and transferrin saturation.
When to consider an iron test
- Suspected iron deficiency or anaemia
- Ongoing tiredness or low energy
- Investigating possible iron overload
- As part of full iron studies
- Monitoring iron treatment
Frequently asked questions
This page is general information about a blood marker and is not medical advice or a diagnosis. An iron test screens and gives context; results are interpreted by a clinician alongside your symptoms, history and other markers. Always follow the guidance on your own report.