Influence of serum transferrin concentration on diagnostic criteria for iron deficiency in chronic heart failure

AimsTransferrin saturation (TSAT), a marker of iron deficiency, reflects both serum concentrations of iron (SIC) and transferrin (STC). TSAT is susceptible to changes in each of these biomarkers. Little is known about determinants of STC and its influence on TSAT and mortality in patients with heart failure. Accordingly, we studied the relationship of STC to clinical characteristics, to markers of iron deficiency and inflammation and to mortality in chronic heart failure (CHF). Methods and resultsProspective cohort of patients with CHF attending a clinic serving a large local population. A total of 4422 patients were included (median age 75 (68-82) years; 40% women; 32% with left ventricular ejection fraction & LE;40%). STC & LE; 2.3 g/L (lowest quartile) was associated with older age, lower SIC and haemoglobin and higher high-sensitivity C-reactive protein, ferritin and N-terminal pro-brain natriuretic peptide compared with those with STC > 2.3 g/L. In the lowest STC quartile, 624 (52%) patients had SIC & LE;13 & mu;mol/L, of whom 38% had TSAT & GE;20%. For patients in the highest STC quartile, TSAT was 13 & mu;mol/L in 185 (17%) patients. STC correlated inversely with ferritin (r = -0.52) and high-sensitivity C-reactive protein (r = -0.17) and directly with albumin (r = 0.29); all P < 0.001. In models adjusted for age, N-terminal pro-brain natriuretic peptide and haemoglobin, both higher SIC (hazard ratio 0.87 [95% CI: 0.81-0.95]) and STC (hazard ratio 0.82 [95% CI: 0.73-0.91]) were associated with lower mortality. SIC was more strongly associated with both anaemia and mortality than either STC or TSAT. ConclusionsMany patients with CHF and a low STC have low SIC even when TSAT is >20% and serum ferritin >100 & mu;g/L; such patients have a high prevalence of anaemia and a poor prognosis and might have iron deficiency but are currently excluded from clinical trials of iron repletion.

Automated summary

This study explored the determinants of transferrin saturation (TSAT) in patients with heart failure, and the influence of serum transferrin concentration (STC) on TSAT and mortality. The results showed that lower STC (≤2.3 g/L) was associated with older age, lower iron concentration, lower hemoglobin, and higher inflammation markers. After adjusting for age, cardiac markers, and hemoglobin, both higher iron concentration and STC were negatively associated with mortality. These patients often have anemia and poor prognosis, but they are currently excluded from clinical trials of iron repletion.