Health Reference LibraryFerritin 400: how concerning is a raised result?
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Ferritin 400 µg/L is raised and needs explaining through a GP appointment, though rarely urgently. Studies of raised ferritin in primary care show that inflammation, liver strain including fatty liver, and alcohol are the likeliest explanations, with genuine iron overload, usually genetic haemochromatosis, the important minority the tests are designed to catch. Transferrin saturation alongside CRP and liver function separates the causes. WHO guidance flags levels above 500 for evaluation in adults who are not healthy. Two rules apply at this level. No iron supplements from any source, and no blood donation until the cause is known.
Free iron and ferritin result interpreter
Enter what you have. Your ferritin alone works; the other fields sharpen the reading. Nothing you enter leaves this device. Nothing is saved. No AI is used, only published UK guideline thresholds.
This tool gives educational interpretation of published evidence. It is not personal dosing advice and it does not diagnose. It knows nothing about your history, symptoms or other results. Interpreting your results over time, alongside everything else about you, is what Nutri365 does.
How it works
At 400 the two explanations for a raised ferritin diverge fully. The common one is cells under strain. Inflamed, fatty or alcohol-exposed cells release ferritin out of proportion to iron, so the number reflects cell stress rather than iron stores. The minority that matters is iron genuinely accumulating, in the UK most often through HFE haemochromatosis, a genetic condition in which absorption fails to reduce as stores rise. In that case transferrin saturation runs high alongside, typically above 45 to 50 percent, which is what the confirmatory blood test looks for. The pathway exists because the two explanations need different responses.
Timing
The work-up sets its own schedule once begun, and the useful contribution from the patient side is the trend, meaning any historical ferritin results with their dates. Where the cause lands on lifestyle, the number responds over months rather than weeks, and a repeat at 3 to 6 months shows it. Where haemochromatosis is confirmed, management is well established, effective, and led by the clinical team from that point.
Safety profile
Certain symptoms upgrade the appointment to prompt. Significant fatigue with joint pains, discomfort under the right ribs, or new diabetes together with skin darkening can accompany established overload. In the absence of symptoms, 400 is an orderly out-patient question rather than an emergency. Two rules are absolute. No iron supplementation in any form, and no assumption that feeling well means the number needs no explanation, because studies show early overload is typically silent.
Special populations
Anyone with Northern European ancestry and relatives with haemochromatosis, liver disease or unexplained joint problems should volunteer that history, because carriage of the C282Y gene variant is common and testable. Regular drinkers and anyone with metabolic risk factors most often find the explanation there, and see ferritin fall as those change. Pre-menopausal women at 400 sit further outside their expected range than men, which strengthens the case for the full work-up. Anyone already under care for an inflammatory or liver condition should route this number through that team.
Guideline positions
WHO guidance from 2020 places its evaluation threshold above 500 µg/L in adults who are not healthy, indicating the need for clinical and laboratory work-up of cause. UK laboratory ranges commonly extend to 300 to 400 for men and lower for women, so 400 sits at or beyond range in most reports. The standard first-line work-up in UK practice pairs a repeat ferritin with CRP, liver function tests and transferrin saturation, with genetic testing for haemochromatosis where saturation is persistently raised.
Practical framework
The first step is booking the GP appointment and letting the standard panel do its work, meaning repeat ferritin, CRP, liver function and transferrin saturation. Three further steps are safe regardless of the results. Remove every incidental iron source, including supplements and fortified products chosen without checking. Reduce alcohol. Gather any older blood results, because the trend over years is diagnostically valuable. Blood donation should not be used as a management strategy until the cause is known, and online advice to self-manage iron overload warrants caution. Nutri365 stores results such as this, reads them over time alongside tracking data and reported symptoms, checks for interactions and contraindications, and refers questions outside scope to a health specialist.
Ferritin thresholds at a glance (UK, µg/L)
| Threshold | Meaning | Source |
|---|---|---|
| Below 15 | Iron deficiency in apparently healthy adults | WHO 2020 |
| Below 30 | Iron deficiency confirmed in UK practice (92% sensitivity, 98% specificity) | NICE CKS / NHS |
| Below 40 | Deficiency highly likely (98% sensitivity and specificity) | NHS guidance |
| Above 50 | Deficiency excluded, unless inflammation is present | NHS guidance |
| Below 70 with inflammation | Deficiency still possible when CRP is raised | WHO 2020 |
| Above 500 | Possible overload or other disease, needs clinical evaluation | WHO 2020 |
Sources
- 2020. WHO guideline on use of ferritin concentrations to assess iron status. World Health Organization.
- 2024. Iron deficiency guidelines. NHS Scotland Right Decisions.
- 2023. Ferritin interpretation, a guide for GPs. Royal United Hospitals NHS (NICE CKS aligned).