The effect of intravenous antibiotics on anaemia in cystic fibrosis

Abstract

Infective exacerbation +0.7 (51) b0.001 Anaemic on admission Infective exacerbation +0.2 (105) 0.047 Not anaemic on admission a Infective exacerbation +0.6 (21) 0.005 Anaemic on admission On iron supplements Infective exacerbation +0.7 (30) b0.001 Anaemic on admission Not on iron supplements Other, varied reasons for admission, −1.6 (8) The report by Hoo and Wildman [1] of their experience of parenteral iron infusions makes cautionary reading. Traditional measure of iron deficiency (serum iron, ferritin, transferrin, transferrin saturation) does not distinguish between “true” iron deficient anaemia and the anaemia of chronic disease caused by the physiological restriction of iron [2]. Dietary iron is absorbed by duodenal enterocytes. It is released into the circulation by the iron exporter protein, ferroportin. When ferroportin activity is low, iron accumulates in enterocytes and is lost when old enterocytes are sloughed into the gut lumen. Ferroportin on the surface ofmacrophages regulates the release of iron, which is recycled when aged red blood cells are destroyed. Ferroportin activity is controlled by hepcidin, a peptide produced by the liver, which also has anti-microbial activity. Hepcidin causes ferroportin internalisation and degradation. So, when hepcidin levels are high, iron accumulates in enterocytes and macrophages, restricting availability to erythropoietic cells and resulting in anaemia [4,5]. Hepcidin levels fall in response to anaemia and hypoxaemia, but increase in response to high levels of interleukin-6 (IL6) found in infection and inflammation [3,4]. Suppressing this inflammatory response will reduce hepcidin and increase iron availability. Therefore, we tested whether treatment of exacerbations with antibiotics resulted in an increase in haemoglobin, without the use of intravenous iron. 200 consecutive admissions of patients between January 2008 and January 2013 with cystic fibrosis were analysed. Haemoglobin concentrations in blood samples taken nearest the admission and discharge dates were compared. Admissions were divided according to reason for admission, and subdivided according to the presence of anaemia on admission and whether the patient was already on oral iron supplements at time of admission. Many admissions for reasons other than treatment of infective exacerbations were brief and only 1 blood sample had been taken and so