Neutrophil gelatinase-associated lipocalin (NGAL) reflects iron status in haemodialysis patients

BACKGROUND: An iron deficiency is often present in haemodialysis (HD) patients; however, although transferrin saturation (TSAT) of <20\% and/or serum ferritin of <200 ng/mL should express iron scarcity, in HD patients high ferritin levels could be related to inflammation rather than reflecting optimal iron stores. METHODS: The aim of the present study was to evaluate serum levels of neutrophil gelatinase-associated lipocalin (NGAL), a small siderophore-binding protein, in a cohort of 56 chronic HD patients in order to determine its possible relationships with iron status. RESULTS: NGAL levels were markedly higher in HD patients than in healthy controls; furthermore, HD patients with TSAT <20\% had lower NGAL values than healthy controls, whereas the correction of iron deficiency by means of chronic i.v. iron administration significantly increased NGAL values from baseline. Findings from univariate and multivariate analyses demonstrated that NGAL was a significant predictor of hsCRP, spKT/V and TSAT. In ROC analysis, a NGAL cut-off level of <or=473 ng/mL had a greater sensitivity and specificity than a ferritin level of <200 ng/mL in identifying iron deficiency among HD patients. CONCLUSIONS: The findings demonstrated that HD patients have altered NGAL values probably because this protein is involved in the maintenance of iron equilibrium. Finally, NGAL might be proposed as a new tool in the assessment of iron deficiency and in the management of iron therapy for HD patients.