Non-anemic iron deficiency predicts prolonged hospitalisation following surgical aortic valve replacement: a single-centre retrospective study

Abstract

Background Iron deficiency has deleterious effects in patients with cardiopulmonary disease, independent of anemia. Low ferritin has been associated with increased mortality in patients undergoing cardiac surgery, but modern indices of iron deficiency need to be explored in this population. Methods We conducted a retrospective single-centre observational study of 250 adults in a UK academic tertiary hospital undergoing median sternotomy for non-emergent isolated aortic valve replacement. We characterised preoperative iron status using measurement of both plasma ferritin and soluble transferrin receptor (sTfR), and examined associations with clinical outcomes. Results Measurement of plasma sTfR gave a prevalence of iron deficiency of 22%. Patients with non-anemic iron deficiency had clinically significant prolongation of total hospital stay (mean increase 2.2 days; 95% CI: 0.5–3.9; P = 0.011) and stay within the cardiac intensive care unit (mean increase 1.3 days; 95% CI: 0.1–2.5; P = 0.039). There were no deaths. Defining iron deficiency as a plasma ferritin < 100 µg/L identified 60% of patients as iron deficient and did not predict length of stay. No significant associations with transfusion requirements were evident using either definition of iron deficiency. Conclusions These findings indicate that when defined using sTfR rather than ferritin, non-anemic iron deficiency predicts prolonged hospitalisation following surgical aortic valve replacement. Further studies are required to clarify the role of contemporary laboratory indices in the identification of preoperative iron deficiency in patients undergoing cardiac surgery. An interventional study of intravenous iron targeted at preoperative non-anemic iron deficiency is warranted.

The complex relationship between iron status and anemia in pregnant and postpartum women in India: Analysis of two Indian study cohorts of uncomplicated pregnancies

“…There is a need to measure iron biomarkers to ascertain the need for supplementation and treatment. Non‐anemic iron deficiency has been shown to be associated with adverse outcomes in non‐pregnant populations 15 . If based on hemoglobin measurement only, pregnant women who are iron deficient but not anemic are not treated for iron deficiency, this would put them at greater risk of developing anemia later and could increase the risk of adverse maternal and fetal outcomes.…”

“…10 Therefore for the postnatal cohort, cut-offs of <30 μg/L, 30-200 μg/L, and >200 μg/L were used, which are suggested clinical cut-offs in pregnancy in the presence of inflammation and have been shown to have 95% sensitivity and 85% specificity in diagnosing iron deficiency in pregnant women. 13,14 sTfR is not influenced by inflammation or pregnancy 10 and has been found to be more reliable than ferritin to measure iron deficiency in the presence of inflammation in the non-pregnant population, 15 but there is no agreed physiological cut-off for this biomarker. Therefore as recommended by the WHO, 16 we used the assay manufacturer guidance to classify postpartum women with sTfR >1.8 mg/L as iron deficient.…”

“…Non-anemic iron deficiency has been shown to be associated with adverse outcomes in non-pregnant populations. 15 If based on hemoglobin measurement only, pregnant women who are iron deficient but not anemic are not treated for iron deficiency, this would put them at greater risk of developing anemia later and could increase the risk of adverse maternal and fetal outcomes. Conversely, others who are anemic but not iron deficient are being unnecessarily supplemented, putting them at risk of being exposed to excess iron.…”

Optimizing diagnosis and treatment of iron deficiency and iron deficiency anemia in women and girls of reproductive age: Clinical opinion

“…It is accurate and, unlike serum ferritin, is not altered by inflammatory conditions. It is considered more accurate than serum ferritin (but not the percent transferrin saturation), a position supported by a recent publication that reported a higher sensitivity for diagnosing nonanemic ID in patients hospitalized for aortic valve replacement 30 . The problem with the transferrin receptor is the availability and standardization of results.…”

“…It is considered more accurate than serum ferritin (but not the percent transferrin saturation), a position supported by a recent publication that reported a higher sensitivity for diagnosing nonanemic ID in patients hospitalized for aortic valve replacement. 30 The problem with the transferrin receptor is the availability and standardization of results. Further, in outpatient practices where virtually all of the patients this article is about will be seen, the time for results is considerably longer than that for serum ferritin and TSAT, decreasing convenience and increasing the time to treatment for those in whom iron replacement is indicated.…”