The dynamic effects of preoperative intravenous iron in anaemic patients undergoing surgery for colorectal cancer.

Aim: The aim of this study was to describe the dynamic changes in blood work following individual adjusted dosage of intravenously administered iron(III) isomaltoside in a 4-week period prior to surgery in patients with colorectal cancer.

Methods: This was a single-centre, observational cohort study with prospectively collected data, including patients with colorectal cancer receiving preoperative treatment with iron(III) isomaltoside. Blood samples were taken at baseline, 1 week, 2 weeks and 4 weeks after initial treatment. Sixty-two patients were included in the study.

Results: Sixty-two patients were included for final analysis. The mean increase in haemoglobin was 0.77 g/dl (95% CI 0.52-1.03 g/dl, P < 0.0001) at week 1, 1.5 g/dl (95% CI 1.21-1.80 g/dl, P < 0.0001) at week 2 and 2.13 g/dl (95% CI 1.71-2.55 g/dl, P < 0.0001) at week 4. Patients with severe anaemia (<9.02 g/dl) showed the largest increase in haemoglobin during the treatment course (2.92 g/dl, 95% CI 2.27-3.58 g/dl, P < 0.0001). Patients with mild anaemia (>10.31 g/dl) did not show a significant increase (0.66 g/dl, 95% CI -0.29-1.61 g/dl, P = 0.17). The mean of transferrin saturation after 4 weeks was 8% (95% CI 6%-10%, P < 0.0001).

Conclusions: After intravenously administered iron, patients with severe anaemia had the most substantial increase in haemoglobin, and the increase was largest after 4 weeks. Patients with mild anaemia did not have an increase in haemoglobin during the treatment course. The vast majority of patients still had iron deficiency at surgery 4 weeks after the initial treatment.