Serum Ferritin as An Indicator of Body Iron Stores in Anemic Patients-A Cross-Sectional Study

Abstract

Background: Serum ferritin is widely used as a biomarker for iron status assessment, yet its interpretation remains challenging in various clinical contexts. This study aimed to evaluate the diagnostic performance of serum ferritin across different anemic conditions and establish optimal thresholds for detecting iron deficiency.

Methods: This cross-sectional study included 250 anemic patients (142 females, 108 males; mean age 45.7±16.3 years) classified as having iron deficiency anemia (IDA, n=118), anemia of chronic disease (ACD, n=89), or mixed anemia (n=43). Comprehensive hematological parameters, iron studies, and inflammatory markers were assessed. Bone marrow examination was performed in 75 patients as the reference standard for iron stores.

Results: Median serum ferritin levels differed significantly between groups: 15.4 μg/L in IDA, 278.6 μg/L in ACD, and 65.3 μg/L in mixed anemia (p<0.001). The optimal ferritin cutoff for identifying iron deficiency was 45.2 μg/L in the overall population (sensitivity 86.3%, specificity 92.7%, AUC 0.934). However, this threshold varied substantially by clinical context: 30.5 μg/L in non-inflammatory states (AUC 0.976) versus 78.3 μg/L in inflammatory conditions (AUC 0.869), with even higher thresholds indicated for patients with chronic kidney disease (92.7 μg/L) and elderly patients (68.4 μg/L). Multiple regression analysis identified age, male sex, BMI, inflammatory markers, and comorbidities as independent predictors of serum ferritin levels. Using inflammation-adjusted thresholds significantly improved concordance with bone marrow findings (85.3% vs. 60.0%, κ=0.69 vs. κ=0.17, p<0.001).

Conclusion: While serum ferritin provides valuable information about iron status, its interpretation requires consideration of inflammatory status, demographic factors, and comorbidities. Implementation of context-specific diagnostic thresholds substantially improves its clinical utility. A multiparameter approach incorporating complementary biomarkers offers the most comprehensive assessment of iron metabolism, particularly in complex clinical scenarios.