The detection of iron deficiency in chronic diseases

Abstract

Inflammatory or neoplastic diseases affect the biochemical and haematological parameters generally used to detect iron deficiency (I.D.). Hence, much reliance has been placed on absent stainable iron in marrow fragments and on a positive response to iron therapy in the diagnosis of iron depletion in chronic disease (CD.). Present evidence indicates that neither method reliably detects I.D. in CD. In summary: (i) histochemical and chemical determinations of marrow iron content correlate poorly; (ii) absent stainable marrow iron may occur with substantial iron deposits elsewhere; (iii) response to parenteral iron shows no correlation with other indices of iron stores. Three groups of patients with active rheumatoid arthritis and apparent I.D. were compared. Group A (7 patients) was selected purely on the basis of low serum ferritin levels (6.0 ± 2.3 μg/l, mean ± 1 SD). Groups B and C (9 and 13 patients) taken from the literature, were selected on the basis of absent stainable marrow iron. Their serum ferritin levels were 35 ± 27 μg/1 and 38 ± 19 μg/1. Levels of haemoglobin, serum iron and iron saturation did not suggest the presence of I.D. in any group. However, in Group A values for MCV (66.4 ± 5.7 fl) and TIBC (83 ± 13.4 μmole/1) were characteristic of I.D., whereas in Groups B and C they were intermediate or normal (MCV:71.8 ± 7.4:78.7 ± 8.2 fl: TIBC: 60.5 ± 9.1:71.2 ± 11.2 μmole/1). This study supports the view that absent stainable marrow iron in CD. does not necessarily imply I.D. However, low serum ferritin values (< 12 μg/1) do indicate I.D. and are usually accompanied by appropriate changes in MCV and TIBC. Inflammatory or neoplastic diseases affect the biochemical and haematological parameters generally used to detect iron deficiency (I.D.). Hence, much reliance has been placed on absent stainable iron in marrow fragments and on a positive response to iron therapy in the diagnosis of iron depletion in chronic disease (CD.). Present evidence indicates that neither method reliably detects I.D. in CD. In summary: (i) histochemical and chemical determinations of marrow iron content correlate poorly; (ii) absent stainable marrow iron may occur with substantial iron deposits elsewhere; (iii) response to parenteral iron shows no correlation with other indices of iron stores. Three groups of patients with active rheumatoid arthritis and apparent I.D. were compared. Group A (7 patients) was selected purely on the basis of low serum ferritin levels (6.0 ± 2.3 μg/l, mean ± 1 SD). Groups B and C (9 and 13 patients) taken from the literature, were selected on the basis of absent stainable marrow iron. Their serum ferritin levels were 35 ± 27 μg/1 and 38 ± 19 μg/1. Levels of haemoglobin, serum iron and iron saturation did not suggest the presence of I.D. in any group. However, in Group A values for MCV (66.4 ± 5.7 fl) and TIBC (83 ± 13.4 μmole/1) were characteristic of I.D., whereas in Groups B and C they were intermediate or normal (MCV:71.8 ± 7.4:78.7 ± 8.2 fl: TIBC: 60.5 ± 9.1:71.2 ± 11.2 μmole/1). This study supports the view that absent stainable marrow iron in CD. does not necessarily imply I.D. However, low serum ferritin values (< 12 μg/1) do indicate I.D. and are usually accompanied by appropriate changes in MCV and TIBC.