Influence of intravenous iron therapy on novel markers of iron deficiency

Detection of iron deficiency in patients with end-stage renal disease (ESRD) remains challenging due to the lack of reliable markers. The immature reticulocyte fractions (IRF) RET-Y and RBC-Y may serve as useful novel markers. We investigated the ability of IRF to detect functional iron deficiency in ESRD patients in comparison to Serum ferritin (SF) and Transferrin saturation (TSAT) and the influence of intravenous iron therapy on these markers.

Cross sectional (n=40) and prospective (n=20) studies of hemodialysis patients were performed; 20 patients received intravenous iron (200 mg) monthly and were followed up for 5 months. Iron deficiency was defined as SF < or =200 microg/L and/or TSAT < or =20%. A RBC-Y < or =171 and/or RET-Y < or =168.7 were criteria for iron deficiency. Correlations between traditional and novel markers were examined. Results are given as mean+/-SEM. Paired t-test was used to test for significance.

27 male and 13 female patients, mean age of 56.7+/-3.02 years were enrolled in the cross-sectional study. TSAT correlated with RBC-Y and RET-Y, r=0.47 and 0.61, respectively. Correlations for SF with RBC-Y and RET-Y were r=0.23 and 0.22, respectively. In the prospective component (11 males and 9 females of mean age 60+/-3.4 years), RET-Y and RBC -Y remained stable during iron therapy. The coefficients of variation were RBC-Y 2.54%, RET-Y 4.23%, TSAT 28.74% and SF 35.34%.

RBC-Y and RET-Y correlated with TSAT and SF allowing detection of functional iron deficiency. These measures were less susceptible to fluctuations than traditional markers.