Is a ferritin level of 20 considered low?

Is a Ferritin Level of 20 Considered Low?

Yes, a ferritin level of 20 ng/mL is considered low and indicates iron deficiency that warrants treatment, especially in adults. 1

Understanding Ferritin as a Marker of Iron Status

Ferritin is a protein that reflects iron storage in the body, with each 1 μg/L of serum ferritin corresponding to approximately 10 mg of stored iron. 1

• Serum ferritin is the most specific indicator available for detecting depleted iron stores, particularly when used with other iron status tests. 1
• Ferritin is most accurate as a predictor of iron deficiency when values are extremely low. 1
• Ferritin is also an acute phase reactant, meaning it can be elevated in inflammatory conditions independent of iron status, potentially masking iron deficiency. 1

Clinical Thresholds for Low Ferritin

Different guidelines provide varying thresholds for defining low ferritin, but most consider 20 ng/mL to be low:

• In otherwise healthy adults, ferritin <30 μg/L (30 ng/mL) is considered iron deficient. 2
• For children aged 6-12 years, a cut-off of 15 μg/L is recommended, while for adolescents 12-15 years, 20 μg/L is the threshold. 2
• In chronic kidney disease patients, absolute iron deficiency is defined as serum ferritin <100 ng/mL with transferrin saturation <20%. 1
• In athletes, iron deficiency is defined as serum ferritin <35 μg/L with normal hemoglobin values. 1

Clinical Significance of a Ferritin Level of 20

A ferritin level of 20 ng/mL has several important clinical implications:

• It indicates depleted iron stores even before anemia develops (non-anemic iron deficiency). 2, 3
• This level is below the functional threshold where iron deficiency begins to affect erythropoiesis. 4
• At this level, patients may experience symptoms such as fatigue, irritability, difficulty concentrating, and reduced exercise tolerance, even without anemia. 3
• Functionally-derived limits indicate that iron deficiency anemia starts to occur when ferritin levels reach approximately 10 μg/L. 4

Special Considerations

Several factors can affect the interpretation of ferritin levels:

• In inflammatory conditions, ferritin may be falsely elevated despite iron deficiency. In such cases, a ferritin level up to 100 μg/L may still be consistent with iron deficiency. 5
• Transferrin saturation should be measured alongside ferritin for a more complete assessment of iron status. 1
• The prevalence of iron deficiency is higher in certain populations, including women of reproductive age (38% have non-anemic iron deficiency), pregnant women (up to 84% in third trimester), and patients with chronic conditions like inflammatory bowel disease, chronic kidney disease, heart failure, and cancer. 3

Management Approach

For a ferritin level of 20 ng/mL:

• Treatment is indicated, particularly if symptoms of iron deficiency are present. 2, 3
• Oral iron supplementation (such as ferrous sulfate 325 mg daily or on alternate days) is typically first-line therapy. 3
• Dietary counseling to increase iron intake, particularly from highly bioavailable sources like meat and seafood, is recommended. 1
• Vitamin C should be co-ingested with non-heme iron sources to enhance absorption. 1
• Follow-up testing of ferritin and complete blood count should be performed after 8-10 weeks of treatment to assess response. 2

Pitfalls to Avoid

• Don't ignore low ferritin levels even if hemoglobin is normal, as non-anemic iron deficiency can cause significant symptoms. 2, 3
• Don't fail to investigate the underlying cause of iron deficiency, which may include bleeding, malabsorption, or inadequate dietary intake. 3, 6
• Avoid excessive iron supplementation in patients with normal or high ferritin, as this can be harmful. 2
• Don't rely solely on ferritin for diagnosis in patients with inflammatory conditions; consider additional markers like transferrin saturation. 1, 5