Association of serum total iron-binding capacity and its changes over time with nutritional and clinical outcomes in hemodialysis patients.

Abstract

Serum transferrin, estimated by total iron-binding capacity (TIBC), may be a marker of protein-energy wasting (PEW) in maintenance hemodialysis (MHD) patients. We hypothesized that low TIBC or its fall over time is associated with poor clinical outcomes. In 807 MHD patients in a prospective 5-year cohort, associations of TIBC and its changes over time with outcomes were examined after adjustment for case-mix and markers of iron stores and malnutrition-inflammation including serum interleukin-6, iron and ferritin. Patients with serum TIBC >or=250 mg/dl had higher body mass index, triceps and biceps skinfolds and mid-arm muscle circumference and higher serum levels of iron but lower ferritin and inflammatory markers. Some SF-36 quality of life (QoL) components were worse in the lowest and/or highest TIBC groups. Mortality was incrementally higher in lower TIBC levels (p-trend <0.001). Adjusted death hazard ratio was 1.75 (95% CI: 1.00-3.05, p = 0.05) for TIBC <150 compared to TIBC of 200-250 mg/dl. A fall in TIBC >20 mg/dl over 6 months was associated with a death hazard ratio of 1.57 (95% CI: 1.04-2.36, p = 0.03) compared to the stable TIBC group. Hence, low baseline serum TIBC is associated with iron deficiency, PEW, inflammation, poor QoL and mortality, and its decline over time is independently associated with increased death risk.