What is this test?
Serum iron measures iron circulating on transferrin at the time of collection. It varies during the day and with food, supplements and inflammation, so it is not a reliable measure of iron stores by itself.
Why might it be ordered?
- As part of an investigation of anaemia or possible iron overload.
- To complement ferritin, transferrin or TIBC when assessing iron status.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
Morning and fasting collection may be requested. Report iron supplements and recent infusions, but do not stop treatment without instructions.
How should you understand the result?
Ferritin and transferrin saturation usually add more useful context. A single low serum iron does not prove iron deficiency.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.