Transferrin Saturation
Transferrin Saturation
What this test measures
Transferrin is a protein that carries iron in your blood. Transferrin saturation shows what percentage of your transferrin is carrying iron. This helps assess your iron status.
Understanding the numbers
Typical range: 20-50%
This test is usually done alongside serum iron and ferritin to get a complete picture of iron status.
- Low (iron deficiency): 0–20 %
- Normal: 20–50 %
- Raised: 50–100 %
Key numbers
- 16 % — Below = iron deficiency likely
- 45 % — Above in women = investigate overload
- 50 % — Above in men = investigate overload
- 55 % — Haemochromatosis screening threshold
British Society for Haematology recommends screening for hereditary haemochromatosis when transferrin saturation is persistently above 45% (women) or 50% (men), especially with raised ferritin or a family history. A low saturation (<16-20%) points to iron deficiency even when ferritin is confused by inflammation.
Ranges can vary slightly between laboratories — your report may show slightly different numbers. This page does not read or interpret your result; your GP looks at it alongside your history and other tests.
What a higher-than-normal result can mean
- You may have too much iron in your blood
- Can suggest haemochromatosis (iron overload condition)
- May need further tests to investigate
- Your GP may want to check if this is inherited
Questions you could ask your GP
- What do my iron studies show overall?
- Do I need iron supplements?
- Should I be tested for haemochromatosis?
- What dietary changes would help?
Example stories
These are made-up examples to show how results are talked about in real appointments. They are not real patients.
High saturation — hereditary haemochromatosis
Sam's transferrin saturation was 72% on two occasions, ferritin 680, and his sister had been diagnosed with haemochromatosis.
What the GP said: “This fits hereditary haemochromatosis. I'll do an HFE gene test and refer you to the clinic for venesection.”
What happened next: HFE was positive. Sam had regular venesection and his ferritin fell to 100 over a year. His children were offered cascade testing.
Transferrin saturation above 45-50% — especially with a family history — is the strongest iron-studies clue for haemochromatosis. Family members can be screened and treated early, preventing damage.
Low saturation with inflammation — true iron deficiency
Priya had active Crohn's disease. Ferritin was 140 (raised by inflammation), but transferrin saturation was 12%.
What the GP said: “Despite the normal-looking ferritin, your low saturation tells us you are truly iron-deficient. Oral iron doesn't absorb well with your gut disease — I'll refer you for IV iron.”
What happened next: After IV iron her saturation rose to 28% and her haemoglobin recovered.
In inflammation, ferritin lies — transferrin saturation doesn't, as much. A low saturation means genuine iron deficiency even when ferritin looks reassuring.
Low saturation, heavy periods
Natalie's saturation was 10% and ferritin was 6. Heavy periods and tiredness.
What the GP said: “Both tests agree — straightforward iron deficiency. Iron tablets and a plan for the heavy periods.”
What happened next: After 6 months of iron and a Mirena coil, her iron studies were normal.
When ferritin and transferrin saturation both point to iron deficiency, the diagnosis is clear and treatment is straightforward.
Persistent high saturation without a clear cause
Winston's transferrin saturation was 58% and ferritin 310. No family history. Drank moderate alcohol.
What the GP said: “A mildly raised saturation and ferritin in someone drinking moderately is often alcohol or early overload. I'll check the HFE gene and advise cutting alcohol to see if the numbers settle.”
What happened next: HFE was negative. Winston reduced alcohol and his saturation came down to 42% and ferritin to 180 over nine months.
A mildly raised transferrin saturation isn't always haemochromatosis — alcohol, liver disease and certain medicines can push it up. HFE testing plus lifestyle changes usually clarify the picture.
Before you act on anything here
This page is general information, written to help you understand — it is not personal medical advice and it cannot tell you what is right for you. Talk to your own GP, pharmacist or nurse about your own health.
- Need help now but it's not an emergency? Call NHS 111 or use 111.nhs.uk.
- Emergency? Call 999 or go to A&E.