# Ferritin

Source: https://synapse-lifestyle.com/en/reference-guide/biomarkers/ferritin

Unit: μg/L

## What is Ferritin?

Ferritin is your iron store: the reserve your body keeps for later. It says more about your store than a single iron measurement. Enough iron feeds your energy, concentration and the production of red blood cells. Too little can cause fatigue; a great deal can point to inflammation.

## Clinical frame

**Ferritin is the measure of iron stores**: a small, proportional fraction of the storage protein leaks into the plasma. A low ferritin is almost always specific for depleted stores. Without inflammation, a value below 30 μg/L reliably indicates iron deficiency, a threshold that replaces the historical laboratory limits, which were too low [1] [2].

Ferritin is, however, also an **acute-phase protein**: inflammation, liver disease, kidney failure and cancer raise it and can mask a true deficiency. With inflammation the threshold shifts to 100 μg/L and transferrin saturation (below 20 %) is more reliable for demonstrating iron restriction [1].

A raised ferritin is common and usually not iron overload: the most frequent cause is **metabolic hyperferritinaemia** in metabolic syndrome, fatty liver, obesity and daily alcohol use, alongside inflammation and liver disease. Consider haemochromatosis when transferrin saturation is persistently raised, to be confirmed by HFE genotyping [3].

## What moves this value?

Blood loss (for example menstruation), little iron in the diet or a period of inflammation can make the value fall or rise.

Iron-rich food (meat, legumes, green vegetables) with a little vitamin C alongside steadily replenishes the store. Easy to measure again after a few months.

## What this connects

- [Hemoglobin](https://synapse-lifestyle.com/en/reference-guide/biomarkers/hemoglobin)
- [hsCRP](https://synapse-lifestyle.com/en/reference-guide/biomarkers/hs-crp)
- [Iron](https://synapse-lifestyle.com/en/reference-guide/biomarkers/iron)

Developed and reviewed with the Synapse [medical advisory board](https://synapse-lifestyle.com/en/advisory-board).

## References

1. Fletcher, A., Forbes, A., Svenson, N. & Wayne Thomas, D. Guideline for the laboratory diagnosis of iron deficiency in adults (excluding pregnancy) and children. Br J Haematol 196, 523–529 (2022). https://doi.org/10.1111/bjh.17900
2. Truong, J. et al. The origin of ferritin reference intervals: a systematic review. Lancet Haematol 11, e530–e539 (2024). https://doi.org/10.1016/S2352-3026(24)00103-0
3. Valenti, L. et al. Consensus Statement on the definition and classification of metabolic hyperferritinaemia. Nat Rev Endocrinol 19, 299–310 (2023). https://doi.org/10.1038/s41574-023-00807-6

- [Read more in the reference guide](https://synapse-lifestyle.com/en/reference-guide/heart#Consequence-CSInflammation-FCRP)
- [All biomarkers in the guide](https://synapse-lifestyle.com/en/reference-guide#biomarkers)

The colour zones are personal: they depend on age, sex, risk and history, and appear in the patient's own report.

Insights to discuss with the patient, not a diagnostic instrument.