Labile plasma iron as an indicator of patient adherence to iron chelation treatment.

Poor adherence of transfusion-dependent patients to chelation treatment is often the cause of persistent iron overload and ensuing morbidity. However, a tool to assess patient compliance with therapy is lacking in clinical practice. Labile plasma iron (LPI, the redox-active component of non-transferrin bound iron) has been studied as an indicator of systemic iron overload and of chelation efficacy, and may particularly reflect recent iron equilibrium. We considered the use of LPI as a potential indicator for recent chelation treatment in 18 transfusion-dependent pediatric patients. Samples were collected under chelation treatment or after a short interruption of the treatment, and LPI was measured by the FeROS assay (Aferrix, Tel Aviv, Israel). LPI was significantly higher after a short-term interruption of the chelation (median of 0.4 µM off-therapy [range:0-4] vs 0 µM on-therapy [range:0-2.8] (p < .001)). Conversely, serum iron, serum ferritin and calculated transferrin saturation were not significantly higher in the "off-therapy" samples compared to "on-therapy". In addition, in multivariate logistic regression analysis LPI was the variable most significantly associated with recent chelation treatment (p = .001). We conclude that LPI could serve as a useful indicator of compliance to chelation therapy.