Iron and haematology . Patient guide
Serum Iron
What is Serum Iron
Serum iron measures the iron currently circulating in the bloodstream, bound to its transport protein transferrin. It is part of the full iron studies panel together with ferritin, TIBC, and transferrin saturation, and it has a strong diurnal rhythm so morning sampling is preferred.
This biomarker entry is being clinically reviewed by our team. The factual content draws on UK guidance (NICE, NHS, Royal Colleges and the relevant speciality society where cited).
Reference range
Reported in µmol/L (also seen as µg/dL (multiply µmol/L by 5.6)). Final reports always carry the issuing laboratory's range, which is what your clinician will interpret against.
| Group | Range | Note |
|---|---|---|
| Adult men | 11 to 30 | µmol/L; sample in the morning |
| Adult women (pre-menopause) | 9 to 30 | |
| Adult women (post-menopause) | 11 to 30 |
What it is
Most iron in the bloodstream is bound to transferrin and being transported between the gut, liver, spleen, and bone marrow. Only a small fraction of total body iron is in the bloodstream at any moment; the rest is stored as ferritin or held in haemoglobin. Serum iron alone does not give a complete picture of iron status, which is why it is interpreted alongside ferritin and TIBC.
Why a clinician would order it
Serum iron is requested as part of comprehensive iron studies in the work-up of anaemia, fatigue, hair shedding, or suspected iron overload. It is more useful for distinguishing iron deficiency anaemia from other anaemias than for diagnosing simple iron deficiency, which is more reliably picked up by a low ferritin.
If your level is outside the range
Symptoms of low Serum Iron
- Fatigue, especially with exertion
- Hair shedding
- Breathlessness on stairs
- Pale skin
- Brittle nails
- Symptoms typically overlap with low ferritin
What low can indicate. Iron deficiency (with low ferritin and high TIBC), anaemia of chronic disease (with low TIBC and normal or raised ferritin), recent blood loss, dietary insufficiency, or simply a normal diurnal trough.
Symptoms of high Serum Iron
- Symptoms relate to underlying iron overload: joint pain, fatigue, skin pigmentation change, abdominal discomfort, diabetes
What high can indicate. Iron overload (haemochromatosis), recent iron supplementation, recent blood transfusion, haemolysis releasing iron from red cells, or liver disease.
Testing tips
Morning blood draw essential. Serum iron has a strong diurnal rhythm and afternoon levels can be 30 percent lower. Avoid iron supplements for 24 hours before the test. Interpret alongside ferritin and TIBC for the full picture (a panel of serum iron + TIBC + transferrin saturation + ferritin is the standard UK iron studies).
Where you can get this tested
Serum Iron is included in the following WMG Health panels. Same-day appointments at our Harley Street clinic, with results clinician-reviewed.
Want a specific combination of markers we do not have a panel for? Build a custom panel and our clinicians will design one for you.
Symptoms often investigated with Serum Iron
Serum Iron is commonly tested when patients present with the following symptoms. If any of these resonate with you, the linked guides explain what to look for and which test pathway is appropriate.
Sources
UK guidance our clinicians use when interpreting this marker.
This page is general patient information, not personal medical advice. A GMC-registered clinician will review your results and tailor any interpretation to you. See our Editorial Policy for how we write and review content.
Common questions about Serum Iron
What is a normal Serum Iron range?
Adult men: 11 to 30 (µmol/L; sample in the morning). Adult women (pre-menopause): 9 to 30. Adult women (post-menopause): 11 to 30. Always interpret your own results against the laboratory range printed on your report, since assay-specific reference ranges vary.
What does a low Serum Iron result mean?
Iron deficiency (with low ferritin and high TIBC), anaemia of chronic disease (with low TIBC and normal or raised ferritin), recent blood loss, dietary insufficiency, or simply a normal diurnal trough.
What does a high Serum Iron result mean?
Iron overload (haemochromatosis), recent iron supplementation, recent blood transfusion, haemolysis releasing iron from red cells, or liver disease.
Do I need to fast or prepare for the Serum Iron blood test?
Morning blood draw essential. Serum iron has a strong diurnal rhythm and afternoon levels can be 30 percent lower. Avoid iron supplements for 24 hours before the test. Interpret alongside ferritin and TIBC for the full picture (a panel of serum iron + TIBC + transferrin saturation + ferritin is the standard UK iron studies).
Can I order a Serum Iron blood test privately in London?
Yes. WMG Health offers Serum Iron as part of bespoke panels and several pre-built panels at our 134 Harley Street clinic. Results are clinician-reviewed by a GMC-registered doctor within 4 hours for the most common assays. Bespoke panels from £180; bookings via /contact/ or 020 3239 3378.