Unrecognised iron deficiency in critical illness

Abstract

M C Bellamy and J A Gedney1Bellamy MC Gedney JA Unrecognised iron deficiency in critical illness.Lancet. 1998; 352: 1903Summary Full Text Full Text PDF PubMed Scopus (46) Google Scholar revealed unrecognised iron deficiency in critical illness. Nutritional copper deficiency is also a common clinical feature in patients with severe disability whose commercially available enteral diet contains low amount of copper (0·1 mg/kcal). In such individuals erythrocyte creatine content is a sensitive marker for monitoring of functional copper deficiency.2Okumiya T Jiao Y Saibara T et al.Sensitive enzymatic assay for erythrocyte creatine with production of methylene blue.Clin Chem. 1998; 44: 1489-1496PubMed Google Scholar We measured laboratory tests in 52 patients with severe disability. 26 patients (nine men, 17 women, mean age 78·3 [SD 3·1] years) had been on a low copper enteral diet for longer than 2 years and 26 patients (nine men, 17 women, mean age 78·7 [2·9] years) were on a non-modified diet. There were no significant differences between the groups in serum total protein, total cholesterol, lactate dehydrogenase activity, and platelet count. Patients on a low copper diet had lower values than those on a non-modified diet for: serum caeruloplasmin (88 [65] vs 281 [46] mg/L, Student's t test <0·0001); copper (3·6 [3·8] vs 16·0 [3·1] μmol/L, p<0·001); leucocytes (4·1×103Williams DM Loukopoulos D Lee GR et al.Role of copper in mitochondrial iron metabolism.Blood. 1976; 48: 77-85PubMed Google Scholar vs 5·8×103Williams DM Loukopoulos D Lee GR et al.Role of copper in mitochondrial iron metabolism.Blood. 1976; 48: 77-85PubMed Google Scholar cells/μL, p=0·004); erythrocytes (3·4×106 vs 4·1×106 cells/μL, p=0·0003), and haemoglobin (109 [24] vs 125 [13] g/L, p=0·003). Patients with haemoglobin below 100 g/L were restricted to those on a low copper diet whose serum concentration of copper below 1 μmol/L. Since copper deficiency affects iron metabolism in erythrocytes3Williams DM Loukopoulos D Lee GR et al.Role of copper in mitochondrial iron metabolism.Blood. 1976; 48: 77-85PubMed Google Scholar and increased erythrocyte creatine content is a marker of a decreased life span of erythrocytes in vivo,2Okumiya T Jiao Y Saibara T et al.Sensitive enzymatic assay for erythrocyte creatine with production of methylene blue.Clin Chem. 1998; 44: 1489-1496PubMed Google Scholar we measured erythrocyte creatine content and found it was significantly increased in patients on a low copper diet (2·70 [0·91]v 1·87 [0·51] μmol/g haemoglobin, p=0·0003; normal concentration in healthy adults is 1·18 [0·26] μmol/g) We supplemented copper 1 mg daily for 1 month in eight patients with serum copper below 1 μmol/L, 6 of whom had haemoglobin below 100g/L with increased erythrocyte creatine content of more than 3 μmol/g Haemoglobin concentrations increased greater than 100 g/L and leucocytes above 3000 cells/μL. Supplementation of a small amount of copper is recommended to prevent progressive anaemia and leucocytopenia in patients on a long-term low copper diet. These patients also showed decreased serum iron.