Low Hb Density (LHD %) in the Detection of Latent Iron Deficiency in Non-Anemic Premenopausal Women

Hemoglobin (Hb) within the reference interval does not exclude iron deficiency, because there is a long period of reduced iron stores (latent iron deficiency) before anemia is present. Low Hb density (LHD %) reported by Beckman-Coulter analyzers, derived from the mean cell hemoglobin concentration, is related to iron availability and hemoglobin content. We study the potential utility of LHD% in the detection of the stages of latent iron deficiency, storage iron depletion (SID) and iron deficient erythropoiesis (IDE), when compared to well establish tests. Methods: 1141 women on child-bearing age (mean 31.7 years) where recruited.Concordance of LHD % with ferritin and sTfR was studied with inter-rater agreement test and Pearson ́s correlation; the diagnostic performance with Receiver operating characteristic (ROC) curve analysis. Results: the values of Hb, serum ferritin and sTfR, determined the groups: No Iron deficiency (n=450), SID (n=127), IDE (n=40). LHD% correlation with ferritin R= -0.4896; concordance, κ =0.561. Criteria for SID ferritin< 20 μg/L ROC AUC 0.844 (95% CI 0.729-0.924) , cut off 5.1 % ,sensitivity 83.3 %, specificity 81.2 %, Correlation LHD% and sTfR R= 0.7198, concordance κ =0.665. Criteria for IDE sTfR> 2.2 mg/L. ROC AUC 0.899 (95 % CI0.769 to 0.961), cut off 6.6 %, sensitivity 80.6 %, specificity 92.9 % Conclusion: LHD % is a reliable parameter recognizing subsets of apparently healthy subjects, adding useful information for detecting subclinical iron deficiency in a group at special risk to develop iron deficiency anemia.