Evidence for an independent role of metabolic acidosis on nutritional status in haemodialysis patients

Background: Malnutrition in haemodialysis (HD) patients has been referred to underdialysis with low protein intake, and to acidosis. However, the separate effects of underdialysis and acidosis on nutrition have not been clearly demonstrated. To evaluate the role of the dialysis dose and of metabolic acidosis on nutrition, we measured the predialysis serum HCO3, pH, serum albumin, PCRn, Kt/V, and BMI in 81 uraemic patients on maintenance bicarbonate, HD for 93±80 months. Patients with chronic liver diseases, malignancies, and cachexia were excluded. Results: Mean age was 59±17 years, Kt/V was 1.29±0.21, PCRn 1.06±0.22 g/kg/day, serum albumin 4.07plusmn;0.28 g/dl, BMI 23±4 kg/m², HCO3 21.1±1.9 mmol/l, pH 7.36±0.04. Serum albumin showed a significant direct correlation with: PCRn (P=0.001), HCO3 (P=0.001), pH (P=0.002), but no correlation with Kt/V and BMI. Serum HCO3 correlated inversely with PCRn (P=0.027). Multiple regression analysis confirmed the significant role of serum bicarbonate and age, but not of Kt/V, on serum albumin concentrations. The role of PCRn appeared to be marginal compared to serum bicarbonate in determining serum albumin levels. Dividing patients into two groups, serum albumin was 3.96±0.22 g/dl with HCO3 ⩽20 mmol/l and 4.18±0.31 g/dl in those with serum HCO3⩾23 mmol/l (P=0.002). PCRn in the same groups was respectively 1.14±0.24 g/kg/day and 1.01±0.23 g/kg/day (P=0.03). Most importantly, serum albumin levels did not appear to be affected by the dialysis dose, with Kt/V ranging from 0.90 to 1.88. Conclusions: In HD patients with adequate Kt/V, metabolic acidosis exerts a detrimental effect on serum albumin concentrations partially independently of the protein intake, as evaluated by PCRn. In the presence of moderate to severe metabolic acidosis, PCRn does not reflect the real dietary protein intake of the patients, probably as a result of increased catabolism of endogenous proteins. For this reason PCRn should be considered with caution as an estimate of the dietary protein intake in HD patients in the presence of metabolic acidosis.      

Erythropoietin requirements: a comparative multicenter study between peritoneal dialysis and hemodialysis

BACKGROUND: The management of anemia with erythropoietin (EPO) is important in the global treatment of dialysis patients. There is a general impression that anemia control with EPO is obtained more easily in peritoneal dialysis (PD) patients than in hemodialysis (HD) patients. The EPO administration route has to be the same to compare the two techniques adequately. METHODS: To compare EPO action by subcutaneous (SC) route in HD and PD, 132 stable patients were recruited (HD: 69, PD: 63) from six centers, with adequate dialysis criteria (Kt/V in HD >1.3; weekly Kt/V in PD >1.8). In a cross-sectional study, the EPO dose/week, the number of EPO doses/week, hemoglobin (Hb), ferritin, transferrin saturation index (TS), albumin and intact parathyroid hormone (iPTH) were analyzed. Iron treatment, comorbidity and ACE inhibitors (ACEI) and angiotensin II antagonist (AIIA) treatment were recorded. A multivariate regression model was used in the statistical analysis. RESULTS: The mean Hb level was the same in both groups, HD 11.6 (1.3) g/dL, PD 11.4 (1.4) g/dL, p=0.3. The SC, EPO doses required to obtain the Hb levels were higher in HD than in PD patients, with a difference of 64.3 u/Kg/week, statistically significant in the multivariate regression model (p=0.001, 95% CI 42.6-86.0). The number of EPO doses/week was also higher in HD patients (65% of HD patients with > or = 3 doses, 19% of PD patients with three or more doses, p<0.001). TS was similar in both groups, while ferritin was higher in HD patients, with a higher percentage of HD patients using intravenous (i.v.) iron (HD 77% vs. PD 49%, p=0.001). Serum albumin and iPTH were lower in PD patients (p<0.001 and p=0.04, respectively), but the percentage of patients with intact parathyroid hormone (iPTH) >500 pg/mL was similar in both groups (HD 17%, PD 14%). CONCLUSIONS: With the same administration route, PD patients showed a reduced EPO requirement, and less frequent EPO administration than HD patients, to obtain the same Hb level. No other factors, except those involved in better depuration of erythropoiesis inhibitors in PD, seemed responsible for the different EPO requirements.     

Lower erythropoietin and iron supplementation are required in hemodialysis patients with hepatitis C virus infection

BACKGROUND: Chronic hepatitis C virus (HCV) infection is a common infectious agent in chronic hemodialysis (HD) patients. In this prospective case-control study, we aimed to investigate the influence of chronic HCV infection on erythropoietin (EPO) and iron requirement in HD patients. PATIENTS AND METHODS: 49 HD patients (24 male, 25 female, mean age 47 +/- 15 years) were included. The mean time spent on dialysis was 39 +/- 38 months, and follow-up time was 1 year for this study. Biochemical analyses and complete blood counts together with iron status of the patients (transferrin saturation and serum ferritin levels) were measured monthly. Highly sensitive C-reactive protein (hs-CRP) levels were measured within 3-month intervals. Endogenous EPO levels were measured by enzyme-linked immunoassay 2 weeks after cessation of EPO treatment. RESULTS: Eleven of the HD patients (22%) were anti-HCV(+). There was no difference in age, sex, time on dialysis, distribution of primary renal diseases, predialytic BUN, Kt/V, albumin and i-PTH levels between HCV(+) and (-) patients. Anti-HCV-positive patients required significantly lower weekly doses of EPO (87 +/- 25 IU/kg vs 129 +/- 11 IU/kg, p = 0.042) and iron (16.8 +/- 12.2 mg vs 32.6 +/- 16.1 mg, p = 0.02) replacement than anti-HCV(-) group; hs-CRP levels were similar between study groups. Serum endogenous EPO levels were significantly higher in HCV(+) patients than HCV(-) HD patients (9.43 +/- 6.47 mU/ml vs 3.59 +/- 2.08 mU/ml, p = 0.008). CONCLUSION: Anti-HCV(+) HD patients had higher serum EPO levels and required less EPO and iron replacement as compared to anti-HCV(-) patients. Because of the changes in iron metabolism, iron treatment should be carefully administered in HD patients with HCV.     

Recombinant human erythropoietin independence in chronic hemodialysis patients: clinical features, iron homeostasis and erythropoiesis

AIMS: Recombinant human erythropoietin (r-HuEPO) is widely used to correct renal anemia in uremic patients. Interestingly, some chronic hemodialysis (HD) patients can maintain high hemoglobin level without the need of r-HuEPO. The aim of this study is to investigate clinical features, iron metabolism and erythropoiesis of these r-HuEPO-independent HD patients. METHODS: r-HuEPO independence was defined in dialysis patients as hemoglobin greater than 12 g/dl and no use of r-HuEPO for at least 6 months. An age- and sex-matched group was selected for comparison. Their underlying diseases, duration of hemodialysis therapy, efficacy of dialysis (Kt/V), normalized protein catabolic rate (nPCR) and body mass index (BMI) were recorded. Laboratory data including: hemoglobin, albumin, high sensitivity C-reactive protein, serum iron, total iron binding capacity, transferrin saturation, ferritin, intact parathyroid hormone, soluble transferrin receptor (sTfR), serum EPO, cortisol, testosterone, aluminum and leptin levels were measured. Renal sonography was also performed in each patient to evaluate renal cyst formation. RESULTS: About 2.3% of all HD patients (21/888; M : F = 18 : 3) were r-HuEPO-independent. These patients had significantly longer HD duration and higher serum EPO and sTfR levels, and lower transferrin saturation rate than dependent groups. Correlation analysis revealed that hemoglobin level strongly correlated with HD duration, serum sTfR and EPO levels. Levels of sTfR were positively related with serum EPO levels and BMI. Multivariate regression analysis showed that level of sTfR was the only independent factor related to r-HuEPO independence. CONCLUSION: R-HuEPO independence is rare among chronic hemodialysis patients. Factors contributing to this dependence are complex and multiple. Level of serum sTfR parallels erythropoiesis and is the most significant factor associated with r-HuEPO independence in chronic HD patients.     

Soluble transferrin receptor is correlated with erythropoietin sensitivity in dialysis patients.

BACKGROUND: Iron deficiency is the most common cause of erythropoietin (EPO) resistance in dialyzed patients with renal anemia. Subclinical or functional iron deficiency is difficult to diagnose in these patients. The soluble transferrin receptor (sTf-R) is considered as a sensitive and specific indicator of bone marrow iron availability. PATIENTS AND METHODS: To evaluate the clinical usefulness of this novel marker, we investigated relationships between EPO requirements and various hematological and biochemical parameters of erythropoiesis in 27 pediatric end-stage renal failure patients treated by hemodialysis (HD, n = 11) or chronic peritoneal dialysis (PD, n = 16). Iron was substituted intravenously once or twice per week in HD, and by daily oral administration to PD patients. Serum sTf-R concentrations were measured by an enzyme-linked immunosorbent assay. Serum ferritin and transferrin concentrations were determined using nephelometric assays. Hemoglobin and iron levels were estimated by automated procedures. RESULTS: While neither transferrin saturation nor serum ferritin concentrations were indicative of EPO requirements, a highly significant correlation between the EPO efficacy index (EPO dose divided by hemoglobin concentration) and sTf-R was observed (r = 0.65, p = 0.001). The intravenous iron substitution in HD patients was associated with higher ferritin concentrations compared to the orally substituted PD patients (280+/-100 ng/ml vs. 124+/-83 ng/ml, p<0.002). In contrast, sTf-R concentrations were similar in both treatment groups (25.7+/-7.7 nM vs. 27+/-10.8 nM, n.s.), as were hemoglobin concentrations and EPO requirements. CONCLUSION: Our results suggest that sTf-R is a more sensitive indicator of functional iron deficiency and impaired EPO responsiveness than serum ferritin or transferrin saturation in dialyzed patients. Intensified iron substitution to patients with elevated sTf-R concentrations may considerably improve the cost efficacy of EPO treatment.     

Effectiveness of erythropoiesis on supervised intradialytic oral iron and vitamin C therapy is correlated with Kt/V and patient weight

BACKGROUND: Poor compliance to oral medication and diet is common in hemodialysis (HD) patients and limits the ability of oral iron therapy to support erythropoiesis. Intravenous (i.v.) iron may be associated with undesirable and sometimes life-threatening complications. PATIENTS AND METHODS: We hypothesized that intradialytic oral iron therapy can overcome compliance problems and support effective maintenance erythropoiesis, which will keep Hct in the range of 33% to 36% and EPO requirements up to 50 units/week/kg. In a prospective observational study, SC EPO-treated hospital-based HD patients without conditions known to cause EPO resistance, were managed on intradialytic oral administration of iron and vitamin C. The primary endpoints were EPO requirements and resistance to EPO which standardized EPO requirements by the Hct level. Secondary endpoints included parameters that might affect the primary endpoints. Exclusion criteria were refusal to take oral medication, prestudy Hct < 27%, recent i.v. iron therapy or transfusions, bleeding, clinical conditions obligating Hct > 30% and known causes of EPO resistance. Twelve patients completed minimal follow-up period of 9 months. RESULTS: Mean Hct was 34.4% (range: 31.8% - 40.2%). EPO requirements were 61.7 +/- 28.2 units/kg and below 52.5 units/kg in 50% of patients. Patients were classified into equal groups according to resistance to EPO, which was positively correlated (r = 0.71 p < 0.01) with body weight and Kt/V (r = -0.38, p < 0.05). CONCLUSION: In conclusion, intradialytic oral iron therapy can support effective maintenance erythropoiesis in 50% of patients without known causes for EPO resistance. High response to EPO and low EPO requirement are correlated with lower body weight and possibly improved dialysis.     

The relationship between reticulocyte hemoglobin content with C-reactive protein and conventional iron parameters in dialysis patients

Adequate iron stores are a prerequisite for successful erythropoietin (EPO) therapy in hemodialysis (HD) patients. Nevertheless, iron status estimation in HD patients remains problematic, as most parameters are influenced by inflammation. The reticulocyte hemoglobin content (CHr) has recently been proposed as a useful tool in iron status assessment. However, the effect of inflammation on CHr remains unstudied. This study aimed to assess the relationship between CHr with other parameters of iron status as well as with C-reactive protein (CRP). This relationship was studied in all the patients (n=61) at our dialysis unit. CHr was significantly and positively related to transferrin saturation (TS) (rho=0.26; p<0.05) and inversely to the percentage of hypochromic red blood cells (%Hypo) (rho=-0.63; p<0.0001), but not to serum ferritin. CHr was strongly and inversely related to log CRP (rho=-0.50; p<0.0001). Despite the use of maintenance intravenous (i.v.) iron doses and relatively high serum ferritin levels, a large percentage of patients were in a state of functional iron deficiency (%Hypo > or = 6 in 41% of patients and CHr < or = 29 pg in 13% of patients). This percentage was far lower in patients with CRP levels below the detection limit (2 mg/L) (26% and 0%, respectively). In conclusion, CHr is related to both TS and %Hypo, but not to serum ferritin, and is strongly influenced by the presence of inflammation (as determined by CRP). In patients with elevated CRP levels, it is very difficult to reach target iron status levels without exceeding the upper limits for serum ferritin.     

Serum erythropoietin levels and their correlation with the erythropoietic system in hemodialysis patients and renal allograft recipients

BACKGROUND: Following renal transplantation, serum erythropoietin (EPO) levels gradually increase during the first 2 to 3 months. However, some transplant recipients continue to remain anemic. The aim of the present study was to correlate serum EPO concentrations with hematocrit (Hct) and hemoglobin (Hb) levels in hemodialysis (HD) patients and renal allograft recipients. METHODS: In a comparative cross-sectional study, serum EPO concentrations and Hb and Hct levels were measured in 35 chronic HD patients and 40 transplant recipients who had stable kidney function for at least 6 months after transplantation (group 1). The HD patients were further divided based on their recombinant human (rHu) EPO supplementation into those who received rHu EPO during dialysis (group 2A, n=15) and those who were not on rHu EPO (group 2B, n=20). Data are presented as mean values +/- SD. The statistical analysis was performed by SPSS version 11.0 using chi-square, ANOVA, and Pearson correlation tests. A general linear model (GLM) was used to compensate for the effects of age. The P value for significance was set at .05. RESULTS: Group 2B patients tended to be older than groups 1 and 2A (P=.014). The sex ratios were comparable among groups. Mean EPO level was 17.09 +/- 10.99 mIU/mL in recipients, which was comparable with that of HD patients (18.54 +/- 26.18 mIU/mL; P>.05). No significant correlation was observed between the serum EPO concentrations and Hb and Hct levels in recipients (P>.05). When comparing the 3 groups, EPO was not correlated with Hct and Hb in any group. Hb and Hct were significantly higher among HD patients not on rHu EPO therapy (P=.02). GLM, with age as a covariate, did not yield a significant difference between EPO levels of the studied groups (P=.36). CONCLUSIONS: This study showed that serum EPO level was in the normal range in recipients and HD patients. We were not able to find any correlation between Hb and Hct levels and EPO concentrations in any group of patients irrespective of rHu EPO supplementation. Hence, impaired EPO stimulatory effects may be considered a potential contributor to anemia in these patients.     

Reduction in erythropoietin doses by the use of chronic intravenous iron supplementation in iron-replete hemodialysis patients

BACKGROUND: Iron deficiency is the most common cause of suboptimal response to recombinant human erythropoietin (rHuEPO) in chronic hemodialysis (HD) patients. Iron supply can correct this situation, however, optimal dosage, route of administration, and monitoring of iron status during rHuEPO therapy in maintenance HD patients remains controversial. METHODS: We conducted a 12-month intravenous iron substitution trial in 149 iron-replete chronic HD patients receiving subcutaneous rHuEPO therapy. The available iron pool was maintained with 100 mg iron every 2 weeks or 1 month depending on serum ferritin and transferrin saturation levels, the rHuEPO dosage titrated depending on hematocrit (Hct) levels. RESULTS: After 12-month protocol, the Hct increased (28.7 +/- 4.1 vs 27.7 +/- 2.6, p = 0.003), rHuEPO requirement reduced 25% (46.1 +/- 28.9 vs 61.5 +/- 67.8 U/kg/week, p = 0.006), serum ferritin increased (1,383 +/- 727 vs 930 +/- 857 ng/ml, p < 0.001), so did the transferrin saturation (36.1 +/- 12.7 vs 27.5 +/- 12.8%, p < 0.001). The serum albumin decreased slightly but reached statistical significance (4.1 +/- 0.48 vs 4.2 +/- 0.36 g/dl, p = 0.006), so did the cholesterol levels (166 +/- 41 vs 173 +/- 38 mg/dl, p = 0.044) and pre-dialysis creatinine (11.3 +/- 2.3 vs 11.5 +/- 2.4 mg/dl, p = 0.015). Besides, the iPTH levels did not interfere with the rHuEPO dosage reduction and Hct increment in our patients. CONCLUSION: We conclude that maintaining high levels of serum ferritin and transferrin saturation could further reduce the requirement of rHuEPO in chronic HD patients, but the long-term effect of iron overloading to patients' nutritional status must be further evaluated in contrast to the economic saving.     

Variation of clinical and laboratory features in chronic dialysis patients treated with high-flux hemodialysis after switching to online hemodiafiltration

Purpose

The study of online hemodiafiltration (HDF) benefits over high-flux hemodialysis (HD) raises great interest. The purpose was to compare clinical and laboratory parameters in patients treated with HD who were switched to HDF.

Methods

Forty-eight HD patients (study group) were switched to HDF, while other 521 patients remained on HD as a control group. During last 6 HD months and during first year of HDF, we determined in both groups the following parameters: monthly–weekly dialysis time, systolic and diastolic blood pressure, body mass index (BMI), interdialytic body weight gain (IBWG), blood flow rate (Qb), weekly erythropoietin-stimulating agents dose (EPO), single-pool Kt/V, calcium, phosphorus (P), hemoglobin and normalized protein catabolic ration (nPCR), plus every 3 months—albumin, parathormone (PTH), ferritin and transferrin saturation (TSAT). In both groups, parameters in the last 6 HD months were compared to those in the first 6 months and, respectively, to those in the first year of HDF.

Results

In the study group, albumin and nPCR were significantly higher in the HD period not only compared to the first 6 months of HDF, but also compared to the first year of HDF. IBWG and P were higher with HD compared to the first year of HDF, but not with the first 6 months. PTH, Kt/V, Qb and EPO were higher in both HDF periods. In the control group, albumin was significantly higher in the first 6 months after the switch, but it was significantly lower in the first year. BMI, ferritin, PTH, Kt/V, Qb, TSAT and weekly dialysis time were higher in both HDF periods, while nPCR, EPO, SBP and DBP were lower. IBWG and Hb rose only during the first year after the switch, while P was lower in the first year, but not in the first 6 months.

Conclusions

Nutrition, assessed by albumin, nPCR and BMI, was not improved by HDF compared to HD. With HDF, Kt/V and phosphorus control were better, similar results were observed in the control group. A larger EPO dose was needed with HDF for maintaining a similar hemoglobin level.     

Effect of intravenous ascorbic acid medication on serum levels of soluble transferrin receptor in hemodialysis patients

Intravenous ascorbic acid (IVAA) medication has been shown to facilitate iron release from inert depots and subsequently circumvent the defective iron utilization in chronic hemodialysis (HD) patients who are treated with recombinant human erythropoietin (rHuEPO). This study focuses on the effects of IVAA supplementation on serum concentrations of soluble transferrin receptors (TfR) on the basis of the hypothesis that an increase of labile iron in the cytosol will lead to inhibition of TfR expression. First, 138 HD patients were studied to evaluate the interrelation between serum TfR and iron status. In a stepwise multivariate analysis, serum EPO and transferrin saturation (TSAT) were the two independent predictors for serum TfR in HD patients (r(2) = 0.510, P < 0.001). Further analyses showed that the lower the serum EPO and the higher the TSAT, the lower the serum TfR in HD patients who are on maintenance rHuEPO treatment. Second, 36 HD patients were recruited in a randomized, controlled study to receive IVAA (total dose of 2000 mg) or normal saline (placebo) medication. Serum levels of TfR, EPO, and ferritin and TSAT were measured at baseline and within 7 d after starting IVAA or placebo. There were no significant changes in serum EPO and ferritin levels in patients who received either IVAA (n = 18) or placebo (n = 18). Serum TfR levels (P < 0.001) significantly declined with a parallel rise in TSAT (P < 0.05) as compared with presupplemental values within 7 d in IVAA patients before any apparent alteration in hematocrit values, but the changes were not observed in the placebo group. The trend of decreased serum TfR and increased TSAT was similar in IVAA patients with ferritin of <500 microg/L or >500 microg/L. It is concluded that ascorbic acid status can significantly decrease serum TfR concentrations and increase percentage of TSAT, probably through alterations in intracellular iron metabolism.     

The hematocrit-corrected erythrocyte sedimentation rate can be useful in diagnosing inflammation in hemodialysis patients.

BACKGROUND/AIMS: We aimed to determine predictors of erythrocyte sedimentation rate (ESR), and the ESR level pointing to the presence of inflammation in 60 chronic hemodialysis (HD) patients. METHODS/RESULTS: On bivariate analysis, increased Westergren ESR of 62 (4-160) mm/h correlated inversely with hematocrit (Hct) and serum albumin, and positively with age, plasma fibrinogen, serum C-reactive protein (CRP), immunoglobulins A and G, alpha(1)-acid-glycoprotein and alpha(1)-antitrypsin. On multivariable analysis, independent predictors of the ESR were raised CRP (p < 0.0001), low Hct (p < 0.0001), increased fibrinogen (p < 0.0001) and immunoglobulin A (p = 0.009), and older age (p = 0.015). The Hct-corrected ESR level [ESR x (Hct/45)] of 38 (4-91) mm/h was independently predicted by CRP (p < 0.0001), fibrinogen (p < 0.0001), and age (p = 0.001). In the patients with normal CRP and albumin, the Hct-corrected ESR value was normal (23 mm/h) and lower than that of 59 mm/h in the subjects with elevated CRP and hypoalbuminemia. Using these cut-off points, the positive and negative predictive values of the Hct-corrected ESR on the presence of inflammation were 1.0, and its sensitivity and specificity were 100%. CONCLUSION: Increased Westergren ESR in HD patients is associated with activated acute-phase response, anemia, and aging. The Hct-corrected ESR values of 23 and 59 mm/h precisely select the HD patients with severe inflammation from those without.     

腹膜透析患者红细胞生成素低反应的影响因素及其预测价值

目的 分析影响腹膜透析患者红细胞生成素（EPO）治疗反应的因素，并建立回归模型。 方法 114例腹膜透析患者根据每周EPO剂量分为低反应组、正常反应组和高反应组。收集患者临床资料，检测营养及炎性反应指标，进行直线相关和Ordinal等级回归分析。 结果 与高反应组及正常反应组比较， EPO低反应组血红蛋白[（78.11±13.42）比（106.28±23.83）、（96.31±12.33） g/L]、血清白蛋白[（33.98±4.78）比（39.72±4.26）、（35.76±4.88） g/L]水平下降，C反应蛋白（CRP）[（26.08±21.66） 比（5.46±1.75）、（11.82±5.63） mg/L]、血清铁蛋白[（371.08±89.38）比（289.39±76.84）、（323.07±62.46） μg/L]水平升高，差异均有统计学意义 (均P < 0.01)。相关回归分析显示，CRP、血清白蛋白及铁蛋白是EPO治疗反应的显著影响因素(P < 0.05)。根据这些因素建立数学模型，血清白蛋白<30 g/L对EPO治疗低反应的影响最大，高血清铁蛋白、高CRP的影响次之。 结论 血清白蛋白、CRP和铁蛋白水平与EPO治疗反应相关。炎性反应状态和营养不良是导致EPO低反应的主要原因。     

Factors related to erythropoietin hypo-responsiveness in patients on chronic peritoneal dialysis

Background The present study was aimed at investigating the factors related to hypo-responsiveness to erythropoietin in patients on chronic peritoneal dialysis (PD). Methods We studied 44 patients with end-stage renal disease who had been on PD for more than 6 months and on erythropoietin (EPO) ≥6,000 U/week for more than 3 months. We expressed EPO resistance index (ERI) as weekly EPO dose per hematocrit (Hct) per body weight. The dose of EPO was titrated to maintain a target Hct level between 33% and 36%. Patients were divided into two groups according to weekly EPO dose. We compared the various factors in those two groups and, by using correlation and linear regression analysis, investigated factors that might predict EPO resistance. Results There were 13 patients in the EPO <150 U/kg per week group and 31 patients in the EPO ≥150 U/kg per week group. Among those 31 patients, there were five patients on EPO ≥300 U/kg per week. Compared to the EPO <150 U/kg per week group, the EPO ≥150 U/kg per week group had a lower normalized protein catabolic rate (nPCR), lower level of serum albumin and higher C-reactive protein (CRP). Correlation analysis showed that the ERI had a statistically significant correlation with CRP (r = 0.303, P < 0.05), serum albumin (r = −0.26, P < 0.05), parathyroid hormone (PTH) (r = −0.307, P < 0.05) and nPCR (r = −0.259, P < 0.05). These results show that CRP, serum albumin, PTH and nPCR are factors related to hypo-responsiveness. Multiple stepwise linear regression analysis showed that CRP was the most important independent predictor of EPO hypo-responsiveness. Conclusion CRP, serum albumin, nPCR and PTH are factors related to hypo-responsiveness. Inflammation contributes significantly to EPO hypo-responsiveness.     

Correction of metabolic acidosis increases serum albumin concentrations and decreases kinetically evaluated protein intake in haemodialysis patients: a prospective study

Background: Metabolic acidosis in haemodialysis (HD) patients increases whole body protein degradation while the correction of acidosis reduces it. However, the effects of the correction of acidosis on nutrition have not been clearly demonstrated. Study design: In this study we have evaluated the effects of 3 months of correction of metabolic acidosis by oral sodium bicarbonate supplementation on protein catabolic rate (PCRn) and serum albumin concentrations in 12 uraemic patients on maintenance HD for at least 6 months (median 49 months; range 6-243 months). Pre-dialysis serum bicarbonate, arterial pH, serum albumin, total serum proteins, serum creatinine, plasma sodium, haemoglobin, PCRn, Kt/V, and TACurea, were evaluated before and after correction. Results: Serum bicarbonate levels and arterial pH increased respectively from 19.3±0.6 mmol/l to 24.4±1.2 mmol/l (P<0.0001) and 7.34±0.03 to 7.40±0.02 (P<0.0001). Serum albumin increased from 34.9±2.1 g/l to 37.9±2.9 g/l (P<0.01) while PCRn decreased from 1.11±0.17 g/kg/day to 1.03±0.17 g/kg/day (P<0.001). No changes in Kt/V, total serum proteins, serum creatinine, plasma sodium, haemoglobin, body weight, pre dialysis systolic and diastolic blood pressure, and intradialytic weight loss were observed. Conclusions: Our data demonstrate that correction of metabolic acidosis improves serum albumin concentration in HD patients. The correction of acidosis induced a decrease in PCRn values, as evaluated by kinetic criteria, suggesting that in the presence of moderate to severe acidosis this parameter does not reflect the real dietary protein intake of the patients probably as a result of increased catabolism of endogenous proteins. The correction of metabolic acidosis should be considered of paramount importance in HD patients.     

Factors determining the percentage of hypochromic red blood cells in hemodialysis patients.

Factors determining the percentage of hypochromic red blood cells determines iron status in hemodialysis patients. BACKGROUND: Determination of the percentage of hypochromic red blood cells (RBC; %HYPO) has been advocated as a sensitive index of functional iron deficiency during erythropoietin (EPO) therapy in hemodialyzed patients. METHODS: The significance of %HYPO in chronic renal failure was evaluated in 64 chronically hemodialyzed patients. The linear correlation was determined between %HYPO and 13 variables, including age, sex, weight, C-reactive protein (CRP), ferritin, transferrin (Tf), Tf saturation, soluble Tf receptor (sTfR), serum iron (SI), urea, parathormone, dialysis dose (Kt/V), dose of EPO administered (EPO), and absolute reticulocyte count. Multiple regression analyses were then performed to select the parameters that jointly provide the best prediction of %HYPO. RESULTS: Univariate analysis showed significant correlations between %HYPO and iron parameters (sTfR, Tf saturation, SI, and ferritin, in decreasing order), EPO, reticulocyte count, and CRP. Multivariate analysis yielded an equation showing that the variation of %HYPO is essentially associated with the combined changes in sTfR, CRP, and EPO dosage. CONCLUSIONS: %HYPO is a meaningful and inexpensive parameter that reflects the integrated effects of iron stores, inflammation, and erythropoietic stimulation on iron availability in hemodialyzed patients. Among iron exchange parameters, sTfR is the best predictor of %HYPO, followed by Tf saturation, SI, and ferritin.     

Assessment of iron status by erythrocyte ferritin in uremic patients with or without recombinant human erythropoietin therapy.

Erythrocyte ferritin may be a better estimator of iron bioavailability than the conventional markers of iron stores (serum ferritin and transferrin saturation). To investigate the accuracy of these conventional markers in uremic patients compared with erythrocyte ferritin, we studied 29 chronic hemodialysis patients on erythropoietin (EPO) therapy, 18 without EPO therapy, and 22 healthy control subjects. Apart from the red blood cell indices, serum ferritin, transferrin saturation, and erythrocyte ferritin, the analytical study included red blood cell protoporphyrin and plasma aluminum levels. The control group showed erythrocyte ferritin concentrations between 8.3 and 12.5 attograms/cell (95% confidence interval). In the EPO group, red blood cell protoporphyrin correlated negatively with erythrocyte ferritin, but not with serum ferritin or transferrin saturation. In the non-EPO group, serum ferritin, erythrocyte ferritin, and transferrin saturation did not correlate with red blood cell protoporphyrin. Even though erythrocyte ferritin correlated well with serum ferritin in the EPO group (r = 0.61, P = 0.0003), the sensitivity of normal serum ferritin levels (30 to 300 ng/mL) to discard a low erythrocyte ferritin concentration (erythrocyte ferritin less than 7 ag/cell) was 0.53, while the sensitivity of serum ferritin at levels less than 30 ng/mL to indicate an absolute iron deficiency expressed as a low erythrocyte ferritin concentration was 0.28. Only values of serum ferritin and transferrin saturation greater than 300 ng/mL and 35%, respectively, could rule out a relative iron deficiency expressed as a low erythrocyte ferritin and high red blood cell protoporphyrin concentration. Plasma aluminum levels did not correlate with red blood cell protoporphyrin or erythrocyte ferritin levels in either uremic group.(ABSTRACT TRUNCATED AT 250 WORDS)