---
title: "Transferrin saturation below 20 percent: what your result means"
url: https://nutritailor.co.uk/apps/learn/transferrin-saturation-below-20-percent-what-your-result-means
slug: transferrin-saturation-below-20-percent-what-your-result-means
pillar: Iron
publisher: "Nutri Tailor Health Reference Library"
editor: "Henry Bond"
publisher_makes: "Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance"
---

# Transferrin saturation below 20 percent: what your result means

## Summary

A transferrin saturation below 20 percent alongside a ferritin of 30 or more is consistent with iron deficiency even though the ferritin sits above the deficiency threshold, the combination missed when only ferritin is read. Saturation reflects the iron available to tissues right now, and BSG guidance regards it as more reliable than ferritin where inflammation is active. With symptoms, this suggests a GP conversation carrying both numbers plus a CRP, and you can read the panel together, free, with the interpreter on this site.

## How it works

A transferrin saturation below 20 percent alongside a ferritin of 30 or more is consistent with iron deficiency even though the ferritin sits above the deficiency threshold, and this is the combination that is missed when only ferritin is read. Saturation measures how full the transport protein actually is, so it reflects the iron available to tissues right now, and BSG guidance regards it as more reliable than ferritin where inflammation is active, because inflammation inflates ferritin while saturation stays honest.

## Guideline positions

BSG 2021 reads transferrin saturation alongside ferritin: a saturation below 20 percent alongside a ferritin of 30 or more is consistent with iron deficiency even where the ferritin looks acceptable, and saturation is more reliable than ferritin where inflammation is active. At the other end, the AASLD haemochromatosis guideline sets a saturation above 45 percent as the threshold for further evaluation, with EASL 2022 using above 45 percent for women and above 50 percent for men alongside a raised ferritin, and both advise confirming an elevated saturation with a second, fasting determination before anything else.

## Practical framework

A saturation below 20 percent with symptoms suggests a GP conversation carrying both numbers, since the pair reads differently from either alone. A CRP alongside the two settles whether inflammation is distorting the ferritin. Where iron deficiency is confirmed and iron is appropriate, a retest around three months on shows whether the picture is repairing.

You can read your own numbers against these thresholds with the [free blood test result interpreter](free-blood-test-result-interpreter) on this site. It runs entirely on your device, nothing is saved, and pasting your report fills the values in for you.

## Sources

1. Snook J, Bhala N, Beales ILP, Cannings D, Kightley C, Logan RPH, Pritchard DM, Sidhu R, Surgenor S, Thomas W, Verma AM (2021). British Society of Gastroenterology guidelines for the management of iron deficiency anaemia in adults. Gut. PMID: 34497146. DOI: 10.1136/gutjnl-2021-325210.
2. Bacon BR, Adams PC, Kowdley KV, Powell LW, Tavill AS; American Association for the Study of Liver Diseases (2011). Diagnosis and management of hemochromatosis: 2011 practice guideline by the American Association for the Study of Liver Diseases. Hepatology. PMID: 21452290. DOI: 10.1002/hep.24330.
3. European Association for the Study of the Liver (lead authors: Zoller H, Schaefer B, Vanclooster A, Loustaud-Ratti V, Bardou-Jacquet E, Pietrangelo A; et al) (2022). EASL Clinical Practice Guidelines on haemochromatosis. J Hepatol. PMID: 35662478. DOI: 10.1016/j.jhep.2022.03.033.


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Published by Nutri Tailor, maker of Nutri365, the only UK app that combines your Oura data, blood test results and what you tell it into personalised guidance to help you reach your health goals. Details: https://nutritailor.co.uk/apps/learn/nutri365