The impact of preoperative systemic inflammation on the efficacy of intravenous iron infusion to correct anaemia prior to surgery for colorectal cancer

AIM: Intravenous iron is increasingly used prior to surgery for colorectal cancer (CRC) to correct iron deficiency anaemia and reduce blood transfusion. Its utility in functional iron deficiency (FID) or anaemia of inflammation is less clear. This observational study examined post-iron infusion changes in haemoglobin (Hb) based on grouping by C-reactive protein (CRP) and ferritin. METHODS: Anaemic (M:Hb < 130 mg/L, F:Hb < 120 mg/L) patients with CRC receiving iron infusion, within a preoperative anaemia detection and correction protocol, at a single centre between 2016 and 2019 were included. Patients were grouped by iron deficiency (ferritin < 30 μg/L and CRP ≤ 5 mg/L, n = 18), FID (ferritin < 30 μg/L and CRP > 5 mg/L, n = 17), anaemia of inflammation (ferritin ≥ 30 μg/L and CRP > 5 mg/L, n = 6), and anaemia of other causes (ferritin ≥ 30 μg/L and CRP ≤ 5 mg/L, n = 6). Median change in Hb and postoperative day (POD) 1 Hb was compared by Kruskal-Wallis test. RESULTS: Iron-deficient patients had the greatest increase in Hb after infusion (24 mg/L), highest POD 1 Hb (108 mg/L), and required no blood transfusions. Patients with FID had the second greatest increase in Hb (15 mg/L) and second highest POD 1 Hb (103 mg/L). Those with anaemia of inflammation had little increase in Hb after infusion (3 mg/L) and lower POD 1 Hb (102 mg/L) than either iron-deficient group. Those without iron deficiency showed a decrease in haemoglobin after infusion (− 5 mg/L) and lowest POD 1 Hb (95 mg/L). CONCLUSIONS: Preoperative intravenous iron is less efficacious in patients with anaemia of inflammation and FID undergoing surgery for CRC, compared with true iron deficiency. Further understanding of the role of perioperative iron infusions is required for maximum gain from therapy.