What ferritin level is indicative of iron deficiency anemia?

From the Guidelines

A ferritin level below 30 mg/L is indicative of iron deficiency anemia in patients without clinical, endoscopic, or biochemical evidence of active disease. However, in the presence of inflammation, a serum ferritin up to 100 mg/L may still be consistent with iron deficiency 1. This is because inflammation can artificially elevate ferritin levels even in the presence of iron deficiency.

Key Points to Consider

• Ferritin is the primary storage protein for iron in the body, and its concentration in the blood directly correlates with total body iron stores.
• As iron stores become depleted, ferritin levels fall before changes in hemoglobin, hematocrit, or red cell indices become apparent, making it one of the earliest and most sensitive markers for iron deficiency.
• When evaluating potential iron deficiency anemia, it's essential to consider ferritin results alongside other parameters such as hemoglobin, transferrin saturation, and clinical symptoms to establish a complete diagnosis and determine appropriate treatment.
• The European Crohn's and Colitis Organization (ECCO) guidelines recommend iron supplementation in all patients with iron-deficiency anemia, and quality of life improves with the correction of anemia, independent of clinical activity 1.

Diagnostic Thresholds

• In patients without clinical, endoscopic, or biochemical evidence of active disease, serum ferritin <30 mg/L is an appropriate criterion for the diagnosis of iron deficiency anemia.
• In the presence of inflammation, a serum ferritin up to 100 mg/L may still be consistent with iron deficiency.
• If the serum ferritin level is between 30 and 100 mg/L, a combination of true iron deficiency and anemia of chronic disease is likely 1.

From the Research

Ferritin Levels and Iron Deficiency Anemia

• Ferritin levels are used to diagnose iron deficiency anemia, with various studies suggesting different cutoff values for iron deficiency.
• A study published in 2013 2 suggests that ferritin levels < 40 ng/ml indicate iron deficiency.
• Another study from 2025 3 indicates that low serum ferritin (typically <30 ng/mL) in individuals without inflammatory conditions is diagnostic of iron deficiency.
• A 2022 study 4 found that ferritin levels ≤ 50 ng/mL are indicative of early iron deficiency.
• Research from 2009 5 suggests that a ferritin level >50 microg/L can still be consistent with iron deficiency, especially in the presence of coexistent pathology.
• A 2005 study 6 proposes a cutoff value of 22 microg/L for the diagnosis of iron deficiency in community-dwelling older adults.

Variability in Ferritin Cutoff Values

• The cutoff values for ferritin levels indicative of iron deficiency vary across studies, ranging from <22 microg/L to <50 ng/mL.
• These variations may be due to differences in study populations, such as age, presence of inflammatory conditions, or other comorbidities.
• The use of different diagnostic criteria and methodologies, such as the soluble transferrin receptor to hepcidin ratio (sTfR/Hep ratio) or the sTfR-F Index, may also contribute to the variability in ferritin cutoff values 3, 4, 5, 6.
• It is essential to consider these factors when interpreting ferritin levels and diagnosing iron deficiency anemia, as noted in studies 2, 3.