Assessing the Association between Serum Ferritin, Transferrin Saturation, and C-Reactive Protein in Northern Territory Indigenous Australian Patients with High Serum Ferritin on Maintenance Haemodialysis

Abstract

Objective. To determine the significance of high serum ferritin observed in Indigenous Australian patients on maintenance haemodialysis in the Northern Territory, we assessed the relationship between ferritin and transferrin saturation (TSAT) as measures of iron status and ferritin and C-reactive protein (CRP) as markers of inflammation. Methods. We performed a retrospective cohort analysis of data from adult patients (≥18 years) on maintenance haemodialysis (>3 months) from 2004 to 2011. Results. There were 1568 patients. The mean age was 53.9 (11.9) years. 1244 (79.3%) were Indigenous. 44.2% (n = 693) were male. Indigenous patients were younger (mean age [52.3 (11.1) versus 57.4 (15.2), p < 0.001 ]) and had higher CRP [14.7 mg/l (7-35) versus 5.9 mg/l (1.9-17.5), p < 0.001 ], higher median serum ferritin [1069 μg/l (668-1522) versus 794.9 μg/l (558.5-1252.0), p < 0.001 ], but similar transferrin saturation [26% (19-37) versus 28% (20-38), p = 0.516 ]. We observed a small positive correlation between ferritin and TSAT (r 2 = 0.11, p < 0.001), no correlation between ferritin and CRP (r 2 = 0.001, p < 0.001), and positive association between high serum ferritin and TSAT (p < 0.001), Indigenous ethnicity (p < 0.001), urea reduction ratio (p = 0.001), and gender (p < 0.001) after adjustment in mixed regression analysis. Conclusion. Serum ferritin and TSAT may inadequately reflect iron status in this population. The high ferritin was poorly explained by inflammation.