IRON-ABSORPTION IN ERYTHROPOIETIN-TREATED HEMODIALYSIS-PATIENTS - EFFECTS OF IRON AVAILABILITY, INFLAMMATION AND ALUMINUM

Background. The response to recombinant human erythropoietin (rHuEpo) is determined primarily by the availability of iron. In contrast to i. v. iron, oral iron supplementation is often insufficient for an optima l response. Method. We studied iron absorption and the effects of iron status, aluminium status and inflammation in 19 chronic haemodialysis patients on maintenance rHuEpo therapy. Iron mucosal uptake after 24 h, iron retention after 2 weeks and mucosal transfer of iron were dete rmined with a whole-body counter using an oral dose Fe-59. Iron absorp tion was measured once without, and once after the ingestion of 2 g al uminium hydroxide. Results. On the basis of transferrin saturation, tw o groups of dialysis patients were distinguished: a group with a funct ional iron deficiency (n = 9), and an iron-replete group (n = 10). In the iron-deficient dialysis patients group, mucosal uptake, mucosal tr ansfer, and iron retention were 49.9%+/-29.4, 0.73+/-0.29, and 41.6%+/ -32.2, being significantly lower than in a non-uraemic iron deficient population (P<0.01, P<0.05, P<0.01 respectively). In the iron-replete dialysis patients group, mucosal uptake, mucosal transfer, and iron re tention were 20.0+/-12.3, 0.59+/-0.18, and 11.1+/-6.7, mucosal uptake and iron retention being lower than in a normal iron-replete populatio n (P<0.0005 and P<0.003 respectively). Dialysis patients with high C-r eactive protein (CRP) values showed lower iron absorption. Iron absorp tion data correlated significantly with transferrin saturation and CRP in the iron-deficient group, and with serum ferritin in the iron-repl ete group. Iron absorption decreased after an aluminium hydroxide chal lenge in the iron-deficient patients to the lower levels of the iron-r eplete subjects. Body aluminium stores, estimated by the desferrioxami ne test, did not correlate with parameters of iron absorption. Conclus ion. The absorption of iron in dialysis patients is decreased in haemo dialysis patients, which may, at least in part, be due to inflammation . Aluminium ingestion further reduces absorption in functional iron-de ficient patients.