Soluble transferrin receptor concentration is not superior to log ferritin for evaluating erythropoiesis in adolescents with iron deficiency anemia

Abstract

Background This study investigated the associations of soluble transferrin receptor (sTfR), log ferritin, the ratio of sTfR to log ferritin (sTfR-F index), and the log of the ratio of sTfR to ferritin [log(sTfR/F)] vs. reticulocyte production during iron deficiency. Methods Fluorescent intensity of reticulocytes, immature reticulocyte fraction (IRF), reticulocyte maturity index (RMI), sTfR, and serum ferritin were measured in 149 adolescents. Results There were no significant differences in reticulocyte parameters between the iron deficiency anemia (IDA) subjects with sTfR≥4.9 mg/l and those with sTfR<4.9 mg/l. However, IDA subjects with log ferritin <0.73 μg/l exhibited significantly higher mean values for IRF and RMI, compared to those with log ferritin ≥0.73 μg/l (2.75±1.36% vs. 1.45±1.01%, p<0.05; 2.76±1.31% vs. 1.46±1.09%, p<0.05). In the non-IDA group, reticulocytes averaged 0.97±0.31% in subjects with sTfR≥2.1 mg/l, which were significantly above the values in those with sTfR<2.1 mg/l (0.72±0.16%, p=0.005), but no significant differences were observed in reticulocyte parameters between the subjects with log ferritin ≥1.35 μg/l and those with log ferritin <1.35 μg/l. Correlation coefficients of log ferritin vs. RMI ( r=−0.41) were higher than those of sTfR, sTfR-F index, and log(sTfR/F) vs. RMI ( r=0.24, r=0.30, and r=0.28, respectively) in IDA subjects. Conclusion Reticulocytopoiesis is more closely associated with log ferritin value than with sTfR concentrations in IDA patients, although sTfR significantly reflects erythropoietic activity in non-IDA subjects.