Percentage of hypochromic red blood cells as predictor of erythropoietic and iron response after i.v. iron supplementation in maintenance haemodialysis patients

Background. The percentage of hypochromic red blood cells (RBC), defined as those with a cellular haemoglobin <28 g/dl has been suggested to be a sensitive marker of functional iron deficiency in maintenance haemodialysis (HD) patients. Thus, during rHuEpo therapy an increase in hypochromic RBC to >10% would indicate that more intensive iron supplementation may be required. Methods. We investigated 70 HD patients 57.1±15.3 years old and on maintenance HD for 66.3±47.9 months without blood loss from gastrointestinal bleeding or from the vascular access, without surgery and without infectious disease or malignancy. During the study period of 12 weeks, each patient received an i.v. dose of 800 mg ferrogluconate. Haemoglobin, haematocrit, and the percentage of hypochromic RBC were measured before and every 4 weeks after the start of the study; serum ferritin, zinc protoporphyrin (ZPP) and C-reactive protein (CRP) were measured at the beginning (baseline) and end of the study. Results. At baseline the percentage of hypochromic RBC was ⩽5.0% in 28 patients, >5.0 and ⩽10.0% in 25 patients and >10.0% in 17 patients, suggesting functional iron deficiency in at least 42 patients, suggesting functional iron deficiency in at least 42 patients. Nine patients had serum ferritin values <100 &mgr;g/l; nonetheless in these patients the median percentage of hypochromic RBC was 5.9% (range 0.9-14.3%), indicating that an absolute iron deficiency can occur in the presence of normal amounts of hypochromic RBC. There was a significant correlation between serum ferritin levels and hypochromic RBC at the end, but not at the beginning, of the study. However, there was no correlation between ZPP and hypochromic RBC at any time during the study. During i.v. iron supplementation the rHuEpo dose could be reduced by 8.5% in patients with hypochromic RBC ⩽5.0%, by 11.3% in patients with hypochromic RBC>5.0 and ⩽10.0% and by 23.4% in patients with hypochromic RBC>10.0%, demonstrating the benefit of i.v. iron in patients with functional iron deficiency. In HD patients in whom serum ferritin levels remained below 290 &mgr;g/l until the end of the study, a significant reduction of the rHuEpo dosage could be obtained during i.v. iron therapy. This was not the case in patients with serum ferritin >290 &mgr;g/l after iron supplementation. We found that the percentage of hypochromic RBC is the most sensitive parameter for predicting hyporesponsiveness in CPR-positive patients. Finally our data indicate that HD patients with hypochromic RBC>6% and low to moderate increases in serum ferritin levels after i.v. iron supplementation significantly benefit from i.v. iron therapy. Conclusions. Two different aspectsshould be taken into consideration in HD patients treated with rHuEpo and concomitant i.v. iron therapy: (1) response of the erythropoietic system to rHuEpo, and (2) adequate delivery of the supplemented iron to the erythropoietic system. The patient's percentage of hypochromic RBC and increase in serum ferritin after i.v. iron supplementation should be used to decide whether or no i.v. iron should be given and to monitor this type of therapy in HD patients.     

Percentage hypochromic red cells and the response to intravenous iron therapy in anaemic haemodialysis

Introduction: Iron deficiency is commonly encountered in haemodialysis (HD) patients and may be overcome by i.v. therapy. We have examined the percentage hypochromic red cells (%HRC) for predicting response to i.v. iron in subjects with a low serum ferritin. Methods: Prospective study of i.v. iron saccharate (trivalent iron 200 mg/week for 8 weeks) in anaemic (Hb <10 g/dl) HD patients with serum ferritin <100 &mgr;g/l despite oral iron therapy. Response to i.v. iron was assessed by comparing Hb at 0 and 8 weeks according to %HRC at baseline (0-3%, 4-9%, ⩾10%). Results are mean±1 SD. Results: For all subjects (n=82), Hb and ferritin increased between 0 and 8 weeks (8.9±1.0 to 10.1±1.4, P<0.0001; 55±24 to 288±126, P<0.0001). Patients were stratified into three groups according to %HRC at baseline (0-3%, 4-9%, ⩾10%). Hb increased significantly in all three groups. The mean increase in Hb was greater (0-3%, 0.6±1.2; 4-9%, 1.2±1.0; ⩾10%, 1.6±1.4; P=0.02) and the proportion of patients showing a ⩾1 g/dl increase in Hb was greater (0-3%, 27%; 4-9%, 47%; ⩾10%, 67%; P=0.02) in those with the largest %HRC pre-treatment. Conclusion: Intravenous iron therapy is effective in improving Hb in anaemic HD patients with a low ferritin. However, the magnitude of this response and the proportion of patients responding is related to the percentage hypochromic red cells prior to treatment.     

Regular low-dose intravenous iron therapy improves response to erythropoietin in haemodialysis patients

BACKGROUND.: Erythropoietin (Epo) is an effective but expensive treatmentfor anaemia in patients with chronic renal failure. Hyporesponsivenessto Epo, particularly in haemodialysis patients, is most commonlydue to a functional iron deficiency, which is difficult to monitorreliably. METHODS.: Forty-six stable haemodialysis patients, receiving Epo therapy,were commenced on regular low-dose intravenous iron (sodiumferric gluconate complex) at a dose of 62.5 mg/5 ml given asa slow injection post-dialysis twice weekly, weekly, or fort-nightly,according to their serum ferritin levels. Haemoglobin, serumferritin, Epo dose, and iron dose were measured at 6-weeklyintervals over a 6-month period. RESULTS: At the beginning of the study, 12 patients in the group hadferritin levels of less than 100 µg/l, and were thus consideredto potentially have an absolute iron deficiency. The study groupwas therefore split into two subgroups for the purpose of analysis,i.e. the 12 patients with ferritin levels of less than 100 µg/lat the start of the study or ‘low ferritin group’,and the remaining 34 patients with ferritin levels of greaterthan 100 µg/l at the start of the study or ‘normalferritin group’. In the low ferritin group (n=12), intravenous iron therapy increasedserum ferritin levels, and produced a significant rise in haemoglobin,and a significant reduction in Epo dose. (Ferritin pre-iron,median (range) 68 (20–96)µg/l; post-iron, 210.5(91–447)µg/l, P<0.003, Wilcoxon. Haemoglobinpre-iron, 10.05 (8.2–11.9)g/dl; post-iron, 11.0 (9.9–11.9)g/dl,P<0.03. Epo dose pre-iron, 9000 (4000–30000) i.u./week;post-iron, 6000 (2000–10000)i.u./week, P<0.05.) Similar results were obtained in the normal ferritin group (n=34)following intravenous iron therapy, with significant increasesin serum ferntin levels and haemoglobin concentrations, anda significant reduction in Epo dose. (Ferritin pre-iron, 176(103–519) µg/l; post-iron, 304.5 (121–792)µg/l,P<0.0001. Haemoglobin pre-iron, 9.85 (6.5–12.8)g/dl;post-iron: 11.25 (9.9–13.3)g/dl, P<0.0001. Epo dosepre-iron, 6000 (2000–15 000)i.u./week; post-iron, 4000(0–15000)i.u./week, P<0.005.) CONCLUSION.: Regular intravenous iron supplementation in haemodialysis patientsimproves the response to Epo therapy.     

Economic appraisal of maintenance parenteral iron administration in treatment of anaemia in chronic haemodialysis patients

BACKGROUND.: Iron deficiency is common in haemodialysis patients and adequatesupplementation by the oral or parenteral route has been limitedby drug side-effects, absorption, and cost. Intermittent doses of intravenous iron dextran complex are recommendedin patients with inadequate iron stores despite maximal toleratedoral dose. We conducted a prospective study with economic analysisof a regular maintenance intravenous iron regimen in this groupof patients. METHODS.: Fifty patients comprising one-half of our haemodialysis populationrequired intravenous iron treatment, i.e. they failed to achievean arbitrary goal serum ferritin 100 µg/l despite maximaltolerated oral iron dose. After a loading dose of intravenousiron dextran complex (IV-FeD) based on Van Wyck's nomogram (400±300mg) they received a maintenance dose of 100 mg IV-FeD once every2 weeks. Initial goal serum ferritin was set at 100–200µg/l. If no increase in haemoglobin was achieved at thislevel, transferrin saturation was measured to assess bioavailableiron, and when less than 20%, goal serum ferritin was increasedto 200–300 µg/l. Recombinant human erythropoietin(rHuEpo) was used where needed to maintain haemoglobin in the9.5–10.5 g/l range only if ferritin requirements weremet. RESULTS.: Mean haemoglobin rose from 87.7±12.1 to 100.3±13.1g/l (P<0.001, Cl 7.7–17.9) at mean follow-up of 6 months(range 3–15 months). In patients on rHuEpo, dose per patientwas reduced from 96±59 u/kg per week to 63±41u/kg per week, repres enting a 35% dose reduction (P<0.05,Cl 1–65). An annual cost reduction of $3166 CDN was projected;however, in the first year this is offset by the cost of theloading dose of IV-FeD required at the beginning of treatment.No adverse reactions were encountered. CONCLUSIONS.: Iron deficiency is very common in our haemodialysis population,especially in those patients receiving rHuEpo. A carefully monitoredregimen of maintenance parenteral iron is a safe, effective,and economically favourable means of iron supplementation inpatients with insufficient iron stores on maximum toleratedoral supplements.     

The absorption of iron is disturbed in recombinant human erythropoietin-treated peritoneal dialysis patients

Background. Intravenous iron supplementation is often necessary in recombinant human erythropoietin (r-HuEPO)-treated haemodialysis (HD) patients, but rarely in r-HuEPO-treated peritoneal dialysis (PD) patients. This may be due to differences in iron absorption or blood loss. Method. Iron absorption (whole-body counting after ingestion of a radiolabelled iron test dose) and iron metabolism were compared in eight iron-replete r-HuEPO-treated PD patients (serum ferritin 100-500 &mgr;g/l) and 68 healthy iron-replete controls (sufficient iron in bone marrow specimen). Results. Mucosal uptake (13.4±9.8), mucosal transfer (0.34±0.18) and iron retention (4.9±4.0) in PD patients was significantly lower than in controls (42.9±18.8%, P<0.0001, 0.63±0.18, P<0.0001, and 28.0±16.7%, P<0.0001). Conclusion. Iron absorption is impaired in PD patients, as we have shown previously for HD patients. One reason for higher iron needs in HD patients may be higher blood losses due to the dialysis procedure and blood sampling for laboratory tests.     

Hypochromic red cells and reticulocyte haemglobin content as markers of iron-deficient erythropoiesis in patients undergoing chronic haemodialysis.

BACKGROUND: In patients on chronic haemodialysis, because of a non-specific increase in serum ferritin, iron deficiency may be overlooked leading to failure of erythropoietin treatment. A reticulocyte haemglobin content < 26 pg and a percentage of hypochromic red cells > 2.5 have been proposed as markers of iron-deficient erythropoiesis in such subjects, but it is unclear which parameter is superior. METHODS: We measured haematocrit, reticulocyte haemglobin content, ferritin and the percentage of hypochromic red cells over 10-150 days in 36 chronic haemodialysis patients in a university hospital. Transferrin saturation was also measured in a subset of 25 patients; iron deficiency was defined as a transferrin saturation < 15%. RESULTS: The diagnostic sensitivity and specificity of a reticulocyte haemoglobin content < 26 pg in detecting iron deficiency were 100% and 73% respectively, compared with 91% and 54% for a percentage of hypochromic red cells > 2.5. Paradoxical reticulocyte haemglobin concentrations occurred on follow-up in five patients receiving 4000 U erythropoietin per haemodialysis (HD). In three patients, reticulocyte haemglobin content exceeded 26 pg despite a persistent lack of iron. In a fourth, iron gluconate (62.5 mg i.v./HD) increased transferrin saturation to 27% and reduced the percentage of hypochromic red cells from 12 to 4, while reticulocyte haemglobin remained > 30 pg. In the final patient, iron gluconate increased transferrin saturation from 8 to 30% and reduced the percentage of hypochromic red cells from 40 to below 5, but reticulocyte haemglobin content remained < or = 26 pg throughout. CONCLUSIONS: The reticulocyte haemglobin content is superior to the percentage of hypochromic red cells in detecting iron deficiency in haemodialysis patients.     

A parallel, comparative study of intravenous iron versus intravenous ascorbic acid for erythropoietin-hyporesponsive anaemia in haemodialysis patients with iron overload

Background: Functional iron deficiency may develop and cause erythropoietin resistance in haemodialysis patients with iron overload. Controversy remains as to whether intravenous iron medication can improve this hyporesponsiveness due to decreased iron availability, or whether iron therapy will aggravate haemosiderosis. Intravenous administration of ascorbic acid has been shown to effectively circumvent resistant anaemia associated with iron overload in a small preliminary study. To elucidate further the possible mechanisms of this resistance, a parallel, comparative study was conducted to compare the effects of intravenous iron and ascorbate therapies in iron-overloaded haemodialysis patients. Methods: Fifty haemodialysis patients with serum ferritin of >500 &mgr;g/l were randomly divided into two protocols. They were further stratified into controls (Control I, n=11) and intravenous iron group (IVFE, n=15) in protocol I; and into controls (Control II, n=12) and intravenous ascorbic acid group (IVAA, n=12) in protocol II. Controls had a haematocrit of >30% and did not receive any adjuvant therapy. IVFE and IVAA patients were hyporesponsive to erythropoietin and functionally iron deficient. Ferric saccharate (100 mg dose) was administered intravenously post-dialysis on five consecutive dialysis sessions in the first 2 weeks; and ascorbic acid (300 mg dose) thrice a week for 8 weeks. Red cell and iron metabolism indices were examined before and following therapy. Results: Mean values of haematocrit and transferrin saturation were significantly lower, and erythropoietin dose was higher in IVFE and IVAA patients compared to controls. Intravenous iron therapy neither improved erythropoiesis nor reduced erythropoietin dose during 12 weeks. Iron metabolism indices significantly increased at 2 and 6 weeks, but decreased at 12 weeks returning to the baselines. In contrast, mean haematocrit significantly increased from 25.8±0.5 to 30.6±0.6% with a concomitant reduction of 20% in erythropoietin dose after 8 weeks of ascorbate therapy. Serum ferritin modestly fell but with no statistical significance. The enhanced erythropoiesis paralleled a rise in transferrin saturation from 27±3 to 48±6% and serum iron from 70±11 to 107±19 &mgr;g/dl (P<0.05). Conclusions: Short term intravenous iron therapy cannot resolve the issue of functional iron deficiency in haemodialysis patients with iron overload. Intravenous administration of ascorbic acid not only facilitates iron release from storage sites, but also increases iron utilization in the erythron. Our study draws attention to a potential adjuvant therapy, intravenous ascorbic acid, to treat erythropoietin-hyporesponsive anaemia in iron-overloaded patients.     

Monitoring of iron requirements in renal patients on erythropoietin

We studied 38 patients (9 haemodialysis, 18 peritoneal dialysis,11 advanced renal failure) over the first 12 weeks of erythropoietintherapy. In 14 iron-overloaded patients (ferritin >500 µg/l)the haemoglobin (±SEM) increased from 6.74±0.27to 9.85±0.36 g/dl (P<0.0001) entirely by mobilizingiron reserves (reduced from 1,220±73 to 739±111mg, P<0.0001). In the 24 non-overloaded patients (ferritin<500µg/l) the haemoglobin rose similarly from 7.04±0.18to 10.70±0.36 g/dl (P<0.0001), partly from iron reserves(depleted from 200±74 to –44±77mg, P=0.016)and partly from oral iron supplements (305±110 mg). Inthe overloaded patients the ferritin declined from 1057 µg/l(geometric mean, range 504–3699) to 317 µg/l (42–1505,P<0.0001). In the non-overloaded patients it declined from82 µg/l (8–461) to 45 µg/l (5–379, P=0.016).The transferrin saturation (TS) in the overloaded patients appearedto decline from 38.3±7.2% to 24.0±3.7% but thiswas not statistically significant. In the non-overloaded theTS was unchanged (23.3±2.4 before and 28.1±3.6%after treatment). Considering all 38 patients together, thehaemoglobin correlated negatively with the ferritin (r=0.3731,P<0.001) but not with the TS. The TS correlated with theserum ferritin initially (r=0.75, P<0.001) but not afterthe first 4 weeks. At 12 weeks, eight of 15 patients with irondeficiency (ferritin<50 µg/l) had a TS >20%, whereastwo of five patients with persistent iron overload (ferritin>500 µg/l) had a TS <20%. We conclude that (a) inpatients with iron overload, stored iron is utilizable for erythropoiesis;(b) oral iron supplements are necessary and sufficient for mostpatients without iron overload; (c) the serum ferritin is abetter indicator of iron status than the TS for renal patientson erythropoietin.     

The role of iron status markers in predicting response to intravenous iron in haemodialysis patients on maintenance erythropoietin.

BACKGROUND: Iron deficiency (ID) is the main cause of hyporesponsiveness to erythropoietin in haemodialysis patients and its detection is of value since it is easily corrected by intravenous iron. Markers of iron supply to the erythron, including erythrocyte zinc protoporphyrin (Er-ZPP), percentage of hypochromic erythrocytes (Hypo), reticulocyte haemoglobin content (CHr) and soluble transferrin receptor (sTfR), may be more accurate predictors of ID than ferritin (Fer) and transferrin saturation (TSat), but relative diagnostic power and best threshold values are not yet established. METHODS: In 125 haemodialysis patients on maintenance erythropoietin, the diagnostic power of the above parameters was evaluated by ROC curve, multivariate regression, and stepwise discriminant analyses. Diagnosis of ID was based on haemoglobin response to intravenous iron (992 mg as sodium ferric gluconate complex over an 8-week period). RESULTS: Fifty-one patients were considered iron deficient (haemoglobin increase by 1.9+/-0.5 g/dl) and 74 as iron replete (haemoglobin increase by 0.4+/-0.3 g/dl). ROC curve analysis showed that all tests had discriminative ability with the following hierarchy: Hypo (area under curve W=0.930, efficiency 89.6% at cut-off >6%), CHr (W=0.798, efficiency 78.4% at cut-off < or =29 pg), sTfR (W=0.783, efficiency 72.4% at cut-off >1.5 mg/l), Er-ZPP (W=0.773, efficiency 73.0% at cut-off >52 micromol/mol haem), TSat (W=0.758, efficiency 70.4% at cut-off <19%) and ferritin (W=0.633, efficiency 64.0% at cut-off <50 ng/ml). Stepwise discriminant analysis identified Hypo as the only variable with independent diagnostic value, able to classify 87.2% of patients correctly. Additional tests did not substantially improve diagnostic efficiency of Hypo >6% alone. CONCLUSIONS: In haemodialysis patients on maintenance erythropoietin, Hypo >6% is the best currently available marker to identify those who will improve their response after intravenous iron. Cost-effectiveness suggests that this parameter should be a first-line tool to monitor iron requirements in clinical practice.     

Issues related to iron replacement in dialyzed patients

Correction of renal anaemia by erythropoiesis stimulating agents (ESA) had reduced blood transfusion needs and iron overload risk and nowadays most of end-stage renal disease patients treated with dialysis requires i.v. iron supplementation to optimize the action of ESAs. Recommended targets for iron therapy are serum ferritin > 100 microg/l and hypochromic red cells percentage (HRC) < 10 (or transferrin saturation coefficient [TSAT] > 20% or reticulocyte Hb content [CHr] > 29 pg/cell). If i.v. administration is strongly recommended for all dialysis patients, controversies remain for the mode and rhythm of administration. Follow-up should be done every 1 to 3 months with measurement of serum ferritin in order to keep its level < 500 to 800 microg/l. Potential toxicity of chronic exposure to i.v. iron concerns tissue accumulation, consequences of pro-oxidant effects, cardiovascular damage and increased risk of infection but no clinical data unequivocally confirm that iron overload from parenteral iron contributes to all cause morbidity and mortality. In conclusion, i.v. iron should be used to optimize ESA action and could be used safety if dosage is < or = 100 mg/week and serum ferritin < 500 a 800 microg/l.     

Intravenous iron for CAPD populations: proactive or reactive strategies?

BACKGROUND: The European best practice guideline [Nephrol Dial Transplant 1999; 14 (Suppl 5)] (5A) for the management of anaemia suggests that > 85% of the CAPD population should have a haemoglobin level of > 11.0 g/dl. METHODS: We developed and implemented an outpatient-based protocol for intravenous iron sucrose (IV Fe) and erythropoietin (Epo) in CAPD patients showing iron deficiency despite oral iron therapy. We managed a total of 103 patients over 13 months of study. All CAPD patients were included, regardless of co-morbidity. Treatment developed in two phases: in phase 1 (reactive) (months 1-8), patients with markers of iron deficiency (ferritin < 100 ng/ml or ferritin 100-500 and percentage hypochromic red cells (%HRC) > or =5) were converted from oral iron to IV Fe (300 mg) and reviewed after 4-8 weeks according to haemoglobin (Hb). In phase 2 (proactive) (months 9-13), the criteria for iron therapy were extended: ferritin < 150 ng/ml or ferritin 150-500 and %HRC > or = 2. Patients then received IV Fe (200 mg) and were reviewed after 4 weeks according to Hb. RESULTS: The median haemoglobin increased from 11.0 (Inter quartile range, IQR, 10.1-12.6) g/dl to 11.7 (11.0-12.7) g/dl (P = 0.06). The proportion of patients with absolute iron deficiency (ferritin < 100 ng/ml) decreased from 24 to 2%. The percentage of hypochromic red cells (%HRC) decreased from 4 (2-7) to 1 (1-4) (P < 0.01). CONCLUSIONS:An integrated Epo and IV Fe policy increased the number of patients reaching the European guideline from 50 to 75% with no increase in the population median Epo requirements (42 (IQR, 25-95) IU/kg/week vs 45 (27-101) (P = NS)). This study demonstrates the benefit of early (proactive) intervention in achieving population compliance within current guidelines for renal anaemia.     

Does long-term treatment of renal anaemia with recombinant erythropoietin influence oxidative stress in haemodialysed patients?

Background. Patients with end-stage renal failure undergoing haemodialysis (HD) are exposed to oxidative stress. Increased levels of malondialdehyde (MDA) were demonstrated in plasma of uraemic patients, indicating accelerated lipid peroxidation (LPO) as a consequence of multiple pathogenetic factors. The aim of our investigation was to examine the role of renal anaemia in oxidative stress in HD patients. Methods. MDA and 4-hydroxynonenal (HNE) were measured in three groups of patients undergoing HD: group I comprised eight patients with a blood haemoglobin (Hb) <10 g/dl (mean Hb=8.1±1.3 g/dl), and group II were eight patients with a Hb <10 g/dl (mean Hb=12.4±1.9 g/dl); none of these 16 patients had been treated with human recombinant erythropoietin (rHuEpo). Group III comprised 27 patients with a mean Hb of 10.5±1.6 g/dl after long-term rHuEpo treatment. Results. Mean plasma concentrations of both MDA and HNE were significantly higher (P<0.0001) in all 43 HD patients than in 20 healthy controls (MDA 2.85±0.25 vs 0.37± &mgr;M, HNE 0.32± vs 0.10±0.01 &mgr;M). Comprising the three groups, it was shown that HD patients with a Hb <10 g/dl had significantly higher plasma levels of LPO products (MDA 3.81±0.86 &mgr;M, HNE 0.45±0.07 &mgr;M) than HD patients with a Hb > 10 g/dl (MDA 2.77±0.58 &mgr;M, HNE 0.25±0.05 &mgr;M), and than HD patients treated with rHuEpo (MDA 2.50±0.12 &mgr;M, HNE 0.29±0.03 &mgr;M). Furthermore, an inverse correlation between plasma concentration of LPO products and haemoglobin levels was seen (r=0.62, P<0.0001). Conclusion. Radical generation in HD patients might be caused in part by renal anemia itself. Treatment with rHuEpo may decrease radical generation effectively in HD patients due to the increase in the number of red blood cells and blood haemoglobin concentration. Keywords: erythropoietin; haemodialysis; HNE; lipid peroxidation; MDA; renal anaemia      

The use of darbepoetin in infants with chronic renal impairment

Darbepoetin is a newer analogue of epoetin, with a longer half-life, that allows less frequent administration. There are currently no published data available for its use in infants. We report our experience with this drug in infants with chronic renal impairment, weighing less than 8 kg. Infants had baseline haemoglobin (Hb), iron, ferritin and transferrin levels measured. They were started on approximately 0.5 μg/kg per week of darbepoetin. Hb levels were checked every 2–4 weeks, and iron studies were performed every 4 weeks. Iron supplementation was prescribed to maintain ferritin levels >100 μg/l and transferrin saturation levels >20%. Follow up was for 20 weeks. Six infants with a mean weight of 4.08 kg and a mean creatinine of 259 μmol/l were included. Three infants were medically stable throughout the study, and the mean darbepoetin dose was decreased to 0.25 μg/kg per week. Their dosing interval was increased to every 3–4 weeks. The other three infants were less stable and had multiple medical problems, including periods of haemodialysis and surgery. These infants failed to reach target Hb level, despite an increase in the mean dose of darbepoetin to 1.2 μg/kg per week. In conclusion, darbepoetin can be successfully administered to infants with chronic renal insufficiency, but the dose needs to be tailored to each individual. Administration would be facilitated by smaller unidose syringes.     

Desferrioxamine improves burst-forming unit-erythroid (BFU-E) proliferation in haemodialysis patients

Background: In chronic renal failure, desferrioxamine (DFO) may improve erythropoiesis independent from its aluminium (Al) chelating effect. The mechanism of this action is still unknown. Methods: To verify whether DFO influences proliferation of erythropoietic precursors, we studied 10 patients on chronic haemodialysis, free from malignancies or other haematological diseases, iron deficiency, bone marrow fibrosis, and Al toxicity. Al accumulation was excluded by the DFO test. Peripheral blood samples were drawn for basal burst-forming unit-erythroid (BFU-E) assay. Mononuclear cells were isolated by density gradient centrifugation with Ficoll-Hypaque, and incubated for 15 days with three different experimental conditions: (a) low-dose recombinant human erythropoietin (rHuEpo) (3 U/ml); (b) high dose rHuEpo, (30 U/ml); (c) both DFO (167 &mgr;g/ml) and rHuEpo (3 U/ml). We determined TIBC, transferrin, ferritin, reticulocytes, hypochromic erythrocytes, soluble transferrin receptor (sTR), haemoglobin (Hb), and haematocrit (Hct) at baseline and then every 14 days. Patients received 5 mg/kg DFO infused during the last hour of each dialysis session for 6 weeks; six patients remained in the study for an additional 6 more weeks. BFU-E assays were set up after 6 and 12 weeks of DFO therapy. Results: At baseline DFO had small effect on BFU-E proliferation (33.9±25 vs 30.4±25.9) and high-dose rHuEpo had a significant effect (45.15±27 vs 30.4±25.9, P<0.01). After 6 weeks of DFO therapy a significant increase in BFU-E proliferation was observed in all culture conditions (78.25±32 vs 30.45±25.9 standard culture, P<0.01; 110.9±30 vs45.15±27 high dose rHuEpo, P<0.01; 98.75±32 vs 45.15±27 DFO culture, P<0.01). Moreover, the increase in BFU-E proliferation was significant greater with DFO culture than standard culture (P<0.01). The same trend was found at the third BFU-E assay, performed in only six patients, when all culture conditions showed a further increase of erythroid precursor proliferation. However, the DFO culture was not significantly greater than the standard culture, while the high-dose rHuEpo was significantly greater than the DFO culture. Patients in group 1 (n=10), had a significant increase in reticulocytes (1.5±0.6 vs 1.72±0.3, P<0.01) and of hypochromic erythrocytes (HE) (5.6±5.1 vs 14.4±12.7, P<0.01), while sTR, Epo, Hb, and Hct were only minimally increased. Ferritin decreased significantly (448±224 vs 196±215, P<0.01) and TIBC and transferrin were unchanged. Conclusions: Thus DFO increases erythroid activity by BFU-E proliferation and increases reticulocytes in haemodialysis patients. Such an effect may be related to increased iron utilization. DFO may be a useful tool for anaemic patients with good iron stores and without Al overload. Key words: desferrioxamine; erythroid progenitors; erythropoiesis; haemodialysis      

A prospective crossover trial comparing intermittent intravenous and continuous oral iron supplements in peritoneal dialysis patients.

BACKGROUND: Concomitant iron supplementation is required in the great majority of erythropoietin (Epo)-treated patients with end-stage renal failure. Intravenous (i.v.) iron supplementation has been demonstrated to be superior to oral iron therapy in Epo-treated haemodialysis patients, but comparative data in iron-replete peritoneal dialysis (PD) patients are lacking. METHODS: A 12-month, prospective, crossover trial comparing oral and i.v. iron supplementation was conducted in all Princess Alexandra Hospital PD patients who were on a stable dose of Epo, had no identifiable cause of impaired haemopoiesis other than uraemia, and had normal iron stores (transferrin saturation >20% and serum ferritin 100-500 mg/l). Patients received daily oral iron supplements (210 mg elemental iron per day) for 4 months followed by intermittent, outpatient i.v. iron infusions (200 mg every 2 months) for 4 months, followed by a further 4 months of oral iron. Haemoglobin levels and body iron stores were measured monthly. RESULTS: Twenty-eight individuals were entered into the study and 16 patients completed 12 months of follow-up. Using repeated-measures analysis of variance, haemoglobin concentrations increased significantly during the i.v. phase (108+/-3 to 114+/-3 g/l) compared with each of the oral phases (109+/-3 to 108+/-3 g/l and 114+/-3 to 107+/-4 g/l, P<0.05). Similar patterns were seen for both percentage transferrin saturation (23.8+/-2.3 to 30.8+/-3.0%, 24.8+/-2.1 to 23.8+/-2.3%, and 30.8+/-3.0 to 26.8+/-2.1%, respectively, P<0.05) and ferritin (385+/-47 to 544+/-103 mg/l, 317+/-46 to 385+/-47 mg/l, 544+/-103 to 463+/-50 mg/l, respectively, P=0.10). No significant changes in Epo dosages were observed throughout the study. I.v. iron supplementation was associated with a much lower incidence of gastrointestinal disturbances (11 vs 46%, P<0.05), but exceeded the cost of oral iron treatment by 6.5-fold. CONCLUSIONS: Two-monthly i.v. iron infusions represent a practical alternative to oral iron and can be safely administered to PD patients in an outpatient setting. Compared with daily oral therapy, 2-monthly i.v. iron supplementation in PD patients was better tolerated and resulted in superior haemoglobin levels and body iron stores.     

Is zinc protoporphyrin an indicator of iron-deficient erythropoiesis in maintenance haemodialysis patients?

BACKGROUND.: Zinc protoporphyrin (ZPP), a metabolic intermediate generatedin the red blood cell by incorporation of zinc instead of iron,has been suggested to be a sensitive and specific parameterof absolute iron deficiency in haemodialysis (HD) patients. METHODS.: We studied 62 HD patients, 29–86 years old, with ZPP levels>50 µmol/mol haeme (normal value of ZPP <40 µmol/molhaeme) assessing the value of ZPP as a marker of functionaliron deficiency at different cut-off points of ZPP. None ofthe patients had apparent inflammatory disease, infectious disease,or malignancy. ZPP, haemoglobin, iron and ferritin levels weredetermined before, and after a 24-week period of once-weeklyi.v. administration of 40 mg iron, to determine whether ZPPlevels return to normal during adequate iron supplementation(960 mg iron/patient). RESULTS.: There was no significant change in ZPP levels after iron supplementationin patients with a ZPP >50 µmol/mol haeme (96.7±49.8versus 88.4±43.5 µmol/mol haeme before and afteriron administration respectively, P=n.s.). However, in patientswith a ZPP >90 µmol/mol haeme, there was a significantreduction in ZPP levels (141.2±54.5 versus 108.0±48.8µmol/mol haeme, P<0.001). Serum ferritin increasedsignificantly in both groups. There was no correlation betweenZPP and serum ferritin at any time during the study. There wasalso no correlation between serum aluminium levels and ZPP andno significant difference in changes in ZPP in patients receivingdesferrioxamine therapy compared to those not receiving desferrioxaminetherapy. We did find a significant correlation between moderatelyelevated total blood lead concentrations and ZPP levels at theend of the study. The ZPP levels were not significantly differentin the range from 50–110 µmol/mol haeme before andafter i.v. iron supplementation in the responders (10% increaseof haemoglobin or 20% decrease of the recombinant human erythropoietindose) compared with the non-responders. CONCLUSIONS.: Our data indicate that ZPP cannot be used to predict the erythropoieticresponse to iron supplementation. However, ZPP levels may bean indicator of functional iron deficiency due to blockade ofthe reticuloendothelial iron release in haemodialysis patients.     

Efficacy of low‐dose i.v. iron therapy in haemodialysis patients

Aim: i.v. iron therapy is more effective in maintaining adequate iron status in haemodialysis (HD) patients than oral iron therapy (OIT). However, data on lower doses of i.v. iron therapy are insufficient. Methods: A non‐randomized, open‐label study was performed to compare the efficacy of low‐dose (≤50 mg/week of iron sucrose) i.v. iron therapy (LD‐IVIT) with OIT in HD patients with 100–800 µg/L serum ferritin levels over 4 months. Results: Eighty‐nine patients in the LD‐IVIT group (40 men, 49 women; aged 61 ± 13 years) and 30 patients in the oral iron therapy group (17 men, 13 women; aged 59 ± 7 years) were evaluated. After 4 months of each treatment, serum ferritin levels increased from 398 ± 137 to 529 ± 234 µg/L in the LD‐IVIT group (P < 0.01) but decreased from 351 ± 190 to 294 ± 175 µg/L in the OIT group (P < 0.01). In the LD‐IVIT group, transferrin saturation (from 28% ± 11% to 30% ± 14%, P = 0.49), weekly doses of recombinant human erythropoietin (from 5822 ± 2354 to 5636 ± 2306 IU/week, P = 0.48) and haemoglobin (from 101 ± 9 to 103 ± 9 g/L, P = 0.15) levels remained stable. Conclusion: LD‐IVIT may be one of the regimens that may be considered for maintaining iron status in HD patients. However, efficacy of LD‐IVIT should be verified by further randomized study.     

Intermittent versus maintenance iron therapy in children on hemodialysis: a randomized study

In patients with renal anemia, iron therapy can be administered intermittently or regularly at a low dose. We performed a randomized clinical trial in pediatric patients with end-stage renal failure on hemodialysis and absolute or functional iron deficiency. The study group received maintenance iron therapy according to the ferritin serum levels and the control group received intermittent 10-weekly doses. Success was defined as stabilization of ferritin levels between 100 and 800 g/l and transferrin saturation (TSAT) between 20% and 50%, in addition to an increase in the hemoglobin level. The major reason for exclusion was iron overload. The study group received 6 mg/kg per month of parenteral iron [95% confidence interval (CI) 3.3–8.8] and the control group 14.4 mg/kg per month (95% CI 12–16.8) (P<0.001). After 4 months of treatment, ferritin levels increased to 66 g/l (95% CI 69–200) in the study group and to 334 g/l (95% CI 145–522) in the control group (P=0.009). Maintenance therapy and intermittent weekly doses were successful in 73% and 38%, respectively. After 3 months of treatment, hemoglobin levels increased to 10 g/dl, with no difference between the groups. However, in the control group the increase in hemoglobin levels was unsustained, and 3 patients needed transfusion. Patients in the control group had a higher risk of iron overload than patients in the study group (70% vs. 19%). Thus, the regimen based on assessment of serum ferritin levels was more efficient than the intermittent regimen because it increased and maintained the hemoglobin levels with lower iron doses and a lower risk of iron overload.     

The importance of serum transferrin receptor level in the diagnosis of functional iron deficiency due to recombinant human erythropoietin treatment in haemodialysis patients

In haemodialysis (HD) patients, functional iron deficiency frequently appears due to recombinant human erythropoietin (r-HuEPO) treatment. However, the diagnosis of iron deficiency is not always easy in such patients. Recent studies have shown that the serum transferrin receptor (s-TfR) level is a sensitive, quantitative measure of tissue iron deficiency. In this study, we examined the changes in s-TfR levels in patients with iron deficiency anaemia due to r-HuEPO treatment. We compared s-TfR levels of 24 patients with i.v. administered r-HuEPO 50–70 U/kg/dose) at the end of each dialysis session (three times a week) and diagnosed as having iron deficiency anaemia by routine laboratory methods (ferritin<50 μg/l and transferrin saturation<16%) with s-TfR levels of 32 patients not receiving r-HuEPO and without iron deficiency anaemia. Also, 40 healthy volunteer subjects were included in the study as a control group. Serum ferritin and transferrin receptor levels were measured with ELISAs using monoclonal reagents. There were no differences between the two groups with and without iron deficiency anaemia with respect to mean age, body weight, haemodialysis duration, haemoglobin and serum creatinine levels (p>0.05). For s-TfR levels, while no difference was present between the control and the non-iron deficiency groups (p>0.05), the iron deficiency group had higher s-TfR values than those of both the control and non-iron deficiency groups (p<0.001). Besides, there was an inverse correlation between haemoglobin and s-TfR levels in patients with iron deficiency anaemia (r=?0.85, p<0.0001). We conclude that the measurement of s-TfR levels may be useful in the diagnosis of functional iron deficiency in haemodialysis patients receiving r-HuEPO.     

Iron absorption in erythropoietin-treated haemodialysis patients; effects of iron availability, inflammation and aluminium

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 optimal 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 determined with a whole-body counter using an oral dose ⁵⁹Fe. Iron absorption was measured once without, and once after the ingestion of 2 g aluminium hydroxide. Results: On the basis of transferring saturation, two groups of dialysis patients were distinguished: a group with a functional iron deficiency (n=9), and an iron-deficient dialysis patients group, mucosal uptake, mucosal transfer, 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 retention 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 population (P <0.0005 and P <0.003 respectively). Dialysis patients with high C-reactive protein (CRP) values showed lower iron absorption. Iron absorption data correlated significantly with transferrin saturation and CRP in the iron-deficient group, and with serum ferritin in the iron-replete group. Iron absorption decreased after an aluminium hydroxide challenge in the iron-deficient patients to the lower levels of the iron-replete subjects. Body aluminium stores, estimated by the desferrioxamine test, did not correlate with parameters of iron absorption. Conclusion: The absorption of iron in dialysis patients is decreased in haemodialysis patients, which may, at least in part, be due to inflammation. Aluminium ingestion further reduces absorption in functional iron-deficient patients. Key words: anaemia; erythropoietin; iron absorption; haemodialysis