Ferritin interpretation - a guide for GPs (Non-pregnant adults) - Information for Clinicians - Biochemistry department

Q: Why can ferritin be normal or high even when iron stores are absent?

Ferritin can behave differently in the presence of co-existent inflammatory disorders, where it may remain in the normal or elevated range despite absent iron stores.

Q: What ferritin levels confirm iron deficiency anaemia in non-pregnant adults?

Low ferritin confirms iron deficiency anaemia: below 11 ug/L in women and below 24 ug/L in men.

Q: When should transferrin saturation be tested?

When results fall in the indeterminate range or when there is doubt, transferrin saturation can help; values below 16% indicate iron deficiency.

Oct 12, 2026

Uploaded by McGucket

Ferritin is used as a surrogate marker of body iron stores, but inflammatory and other clinical conditions can keep ferritin normal or elevated even when iron stores are absent. The guide explains how to interpret low ferritin in adults, including anaemia definitions, threshold values for confirming iron deficiency, indeterminate ranges, and when to use transferrin saturation. It also lists causes of raised ferritin, approaches to possible iron deficiency with and without anaemia, and recommended initial investigations, monitoring, and referral principles.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages12

Reading Time4 min

AccessFree to download

Background

Ferritin and limitations in inflammatory disease

Low Ferritin

With anaemia

Indeterminate range and when to test transferrin saturation

Confirming iron deficiency anaemia thresholds

Raised Ferritin causes

Initial investigations

Non-anaemic iron deficiency

Symptoms and when GI investigation is warranted

Treatment and monitoring

GP consultation for low ferritin

Causes of iron deficiency

Information for Clinicians Biochemistry department Ferritin interpretation – a guide for GPs (Non-pregnant adults) Background Ferritin is a surrogate measure of body iron stores. In health, the value is directly proportional to the level of iron stores , however in some circumstances, for example inpatients with co-existent inflammatory disorders, ferritin may be within the normal or elevated range even when iron stores are absent. This means that a low ferritin does suggest deficiency but above this threshold clinical evaluation and context is always required. The current laboratory assay for Ferritin is calibrated to the WHO international reference standard. Low Ferritin With Anaemia In many cases, ferritin will have been requested due to finding anaemia. The investigation of anaemia includes assessment of possible iron deficiency anaemia asa differential, with the first line test being ferritin. Anaemia is defined as: • In adult men Hb below 130 g/L. • In non-pregnant adult women Hb below 120 g/L Please note different ranges are applied in pregnancy. Anaemia with low ferritin (<11 ug/L in women, <24 ug/L in men) confirms iron deficiency anaemia (IDA) . Post-menopausal women may have a slightly higher lower limit of normal but assay specific ranges are not available. Comprehensive guidelines are available via NICE Clinical Knowledge Summaries: Anaemia- iron deficiency | Health topics A to Z | CKS | NICE Ferritin thresholds vary according to the local laboratory and there is debate within the literature regarding where the appropriate thresholds should be placed. The local lower limits to define iron deficiency are based on the assay specific lower limit of normal and are fairly robust. Low iron stores slightly above these thresholds may still warrant investigation if anaemia is present. Most would consider that there is an indeterminate range where inflammation or conditions that increase Ferritin should be excluded. We would suggest that 11-100 ug/L in women and 24-100ug/L in men is the range where inflammation, infection or influence from malignancy, renal, liver and heart failure should be excluded. Not every patient requires investigation of ferritin in the indeterminate range; this level can be interpreted as normal where there are no reasons for an acute phase reaction. However, it is important to consider the patient’s history and current status to ensure that cases of iron deficiency are not missed. Where there is doubt, Transferrin Saturation should be tested. Transferrin saturations below 16% indicate iron deficiency. Causes of raised ferritin levels include: • Acute or chronic inflammation. • CKD • Heart failure • Liver disease • Excessive alcohol intake • Malignancy • Hyperthyroidism Initial investigations The flow chart below is a guide based on the British Society for Haematology best practice guide. Figure 1 Investigation of possible iron deficiency anaemia Non-Anaemic iron deficiency Non-anaemic iron deficiency is relatively common. It can present with non-specific symptoms such as: • Fatigue • Poor attention or memory loss • Sore tongue • Poor condition of skin, nails or hair including hair loss • Delayed wound healing • Restless legs syndrome The overall prevalence of significant underlying GI pathology, and in particular of GI malignancy, is low in Non-Anaemic Iron Deficiency (NAID) . In the absence of other pointers, GI investigation generally is not warranted in premenopausal women since the cause is likely to be menstrual blood loss and/or recent pregnancy. The threshold for investigation of NAID should however be low in men, postmenopausal women, and those with GI symptoms or a family history of GI pathology (British Society Gastroenterology) . It is also important to highlight that where there are red flag symptoms, a referral should not be delayed. Waiting for haemoglobin to drop below a normal value inpatients with iron de

FAQs

Why can ferritin be normal or high even when iron stores are absent?

Ferritin can behave differently in the presence of co-existent inflammatory disorders, where it may remain in the normal or elevated range despite absent iron stores.

What ferritin levels confirm iron deficiency anaemia in non-pregnant adults?

Low ferritin confirms iron deficiency anaemia: below 11 ug/L in women and below 24 ug/L in men.

When should transferrin saturation be tested?

When results fall in the indeterminate range or when there is doubt, transferrin saturation can help; values below 16% indicate iron deficiency.

Oct 12, 2026

Uploaded by McGucket