LAUSR

Is serum ferritin a reliable indicator of iron status in elective major surgery patients? We congratulate Hong et al. for their report on the prevalence and causes of pre-operative anaemia in elective major surgery. Their findings confirm what we reported in this journal in 2016, particularly that iron deficiency anaemia is correctible prior to surgery. In a subsequent report, we further showed that pre-operative haemoglobin concentration is a predictor of transfusion requirement in elective joint replacement. The authors also raise the question about the conventional use of a serum ferritin concentration of 100 μg/L cut-off for iron deficiency anaemia. Our 2016 report showed that 46% of our iron deficiency patients had a serum ferritin above 100 μg/L. The presence of comorbidities in a joint replacement population probably led to a higher ferritin concentration. Hence, we would like to ask the authors on whether their data on serum ferritin support the 100 μg/L cut-off? Lastly, we also agree with the authors that serum soluble transferrin receptor level would be a sensitive indicator of iron deficiency. It is a pity that this test is not more generally available.