A ferritin level >50 microg/L is frequently consistent with iron deficiency

Area of Science:

• Clinical Medicine
• Hematology
• Biochemistry

Background:

• The British Society of Gastroenterology (BSG) recommends a serum ferritin cutoff of ≤50 microg/L for diagnosing iron deficiency, implying iron sufficiency above this level.
• This recommendation may be inaccurate in patients with coexistent inflammation, infection, or malignancy.
• The study investigates the validity of this ferritin cutoff in diverse patient groups.

Purpose of the Study:

• To evaluate the accuracy of the BSG's recommended serum ferritin cutoff (≤50 microg/L) for diagnosing iron deficiency in patients with normocytic anemia.
• To compare the diagnostic performance of serum ferritin with the soluble transferrin receptor/Log(10)ferritin (sTfR-F) Index.
• To determine optimal ferritin thresholds for iron deficiency diagnosis in this population.

Main Methods:

• Prospective data collection over 3 years from 198 patients with normocytic anemia.
• Utilized the sTfR-F Index, with an Index ≥2 indicating iron deficiency and Index ≤1 indicating iron repletion.
• Analyzed the positive predictive value (PPV) and negative predictive value (NPV) of different serum ferritin cutoff levels.

Main Results:

• A serum ferritin cutoff of ≤50 microg/L yielded a PPV of 100% but an NPV of only 22%.
• Increasing the ferritin cutoff to 100 microg/L improved the NPV to 34.8% while maintaining a high PPV of 97%.
• Ninety-three patients had an sTfR-F Index ≥2 (iron deficient), and 17 had an Index ≤1 (iron replete).

Conclusions:

• Serum ferritin levels above 50 microg/L do not reliably exclude iron deficiency in patients with normocytic anemia.
• The sTfR-F Index is a valuable tool for assessing iron status in these patients.
• Integrating the sTfR-F Index into diagnostic workups can enhance patient care and improve the accuracy of iron deficiency diagnosis.