Non-transferrin-bound iron induced by myeloablative chemotherapy

Previous studies have suggested that non-transferrin-bound plasma iron (NTBI) is present in patients undergoing cytotoxic chemotherapy, and that this may exacerbate untoward organ damage and increase the risk of bacterial infections following chemotherapy. However, the source of NTBI during myelosuppressive chemotherapy is controversial. In this study we have examined the kinetics of the appearance and disappearance of NTBI with chemotherapy. NTBI was present in only two out of 24 patients prior to chemotherapy but, following chemotherapy, was present in 19 patients, with peak NTBI levels at 5 d after onset of chemotherapy (mean 3.06 microM). Thereafter levels fell, but were still detectable in seven patients 14 d after the end of chemotherapy. The appearance of NTBI was associated with a sudden rise in transferrin saturation, but NTBI was detected on four occasions in the absence of full transferrin saturation. We have also established that daunorubicin cannot itself liberate NTBI from serum. There was no relationship between induced NTBI levels and serum iron or ferritin levels, previous or current blood transfusions, disease stage, or the type of chemotherapy given. The appearance of NTBI following chemotherapy was inverserely related to the fall in reticulocytes and serum transferrin receptor (TfR) levels, suggesting that NTBI formation is a consequence of suspension of erythropoietic activity.