Lack of Non–Transferrin-Bound Iron in Heart Transplant Recipients

Abstract

Background Labile plasma iron (LPI) is a heterogeneous fraction thought to be composed of iron bound to serum albumin, citrate, and other undefined negatively charged ligands called non–transferrin-bound iron (NTBI). It is associated with formation of reactive oxygen species which are implicated in the pathogenesis of myocardial infarction and bacterial infection. Therefore, the measurement of NTBI could serve as an early marker for reactive oxygen species–induced tissue damage. In this study, we assessed the prevalence of NTBI in heart transplant recipients. Methods Complete blood counts, urea, serum lipids, fasting glucose, creatinine, and N-terminal pro–B-type natriuretic peptide were studied by standard laboratory methods in the central laboratory of the hospital. Soluble transferrin receptor was measured using kits from R&D (Abington, UK) and interleukin-6 with kits from Diaclone (Germany). NTBI was assessed in Israel by Aferrix Ltd; LPI ≤0.4 units was considered to be negative. Results In all of the studied patients, NTBI was negative. In the 15 healthy volunteers, all the results were negative. Conclusions In heart allograft recipients there is no evidence of reactive oxygen species–induced tissue damage due to either iron overload from oversupplementation or excessive blood transfusion. However, this particular adverse effect should be taken into account when considering treatment of anemia with iron and/or red blood cell transfusions.