At what level of ferritin should iron supplements be considered?

From the Guidelines

Iron supplements should be considered when ferritin levels fall below 30 ng/mL, as indicated by the most recent guidelines. According to the 2023 ESPEN guideline on clinical nutrition in inflammatory bowel disease 1, serum ferritin <30 mg/L is an appropriate criterion for the diagnosis of iron deficiency anemia in patients without clinical, endoscopic, or biochemical evidence of active disease.

Key Considerations

• In the presence of inflammation, a serum ferritin up to 100 mg/L may still be consistent with iron deficiency, as stated in the ECCO Anemia Statement 1D 1.
• The European Crohn's and Colitis Organization (ECCO) guidelines conclude that intravenous iron is more effective, shows a faster response, and is better tolerated than oral iron, and should be considered as first-line treatment in certain patient groups 1.
• After successful treatment of iron deficiency anemia with intravenous iron, re-treatment with intravenous iron should be initiated as soon as serum ferritin drops below 100 mg/L or hemoglobin below 120 or 130 g/L according to gender, as recommended by the ECCO Anemia Statement 3E 1.

Treatment Approach

• Common oral iron supplements include ferrous sulfate, ferrous gluconate, or ferrous fumarate, typically taken 1-3 times daily between meals with vitamin C to enhance absorption.
• For those who cannot tolerate oral supplements, intravenous iron formulations like iron sucrose or ferric carboxymaltose may be prescribed by a healthcare provider.
• Supplementation should continue until ferritin levels normalize, usually requiring 3-6 months of treatment.
• It's essential to identify and treat the underlying cause of low ferritin, such as blood loss, poor dietary intake, or malabsorption, alongside supplementation.

From the FDA Drug Label

Administer a maintenance dose of 500 mg at 12,24 and 36 weeks if serum ferritin <100 ng/mL or serum ferritin 100-300 ng/mL with transferrin saturation <20%.

• Iron supplements should be considered at a serum ferritin level <100 ng/mL or serum ferritin 100-300 ng/mL with transferrin saturation <20% 2.

From the Research

Ferritin Levels and Iron Deficiency

• The level of ferritin at which iron supplements should be considered varies depending on the individual's health status and the presence of inflammatory conditions 3, 4, 5, 6, 7.
• A ferritin level <30 ng/mL is commonly used as a cutoff for iron deficiency in non-inflammatory conditions 3, 6, 7.
• However, some studies suggest that a ferritin level >50 microg/L can still be consistent with iron deficiency, especially in the presence of coexistent pathology such as inflammation, infection, or malignancy 5.
• In patients with chronic heart failure, a serum ferritin level <100 ng/mL or a transferrin saturation (TSAT) <20% is often used to define iron deficiency, but this criterion has been questioned and a new approach has been proposed 4.
• The use of ferritin as a diagnostic test for iron deficiency and overload is common, but its accuracy can be affected by various factors such as inflammation and infection 6.
• Different ferritin cutoffs have been associated with varying rates of iron deficiency diagnoses in primary care, with higher cutoffs resulting in higher incidence rates 7.

Diagnostic Criteria for Iron Deficiency

• Iron deficiency is typically diagnosed by low serum ferritin (<30 ng/mL) in individuals without inflammatory conditions or by transferrin saturation (TSAT) <20% 3.
• However, the diagnostic criteria for iron deficiency may need to be revised, especially in patients with chronic heart failure, where a TSAT <20% may be a more reliable indicator of iron deficiency 4.
• The integration of the soluble transferrin receptor/log ferritin ratio (sTfR-F Index) in the diagnostic workup of patients with normocytic anemia can improve patient care 5.

Ferritin Cutoffs and Iron Deficiency Diagnoses

• Ferritin cutoffs of 30 and 45 ng/mL have been associated with a substantially higher incidence of iron deficiency compared to 15 ng/mL in primary care patients 7.
• The choice of ferritin cutoff can significantly impact the diagnosis and treatment of iron deficiency, and a harmonization of diagnostic criteria is needed 7.