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.     

血液透析红细胞生成素抵抗患者pro-hepcidin与炎性反应和铁代谢的关系

目的 研究维持性血液透析(MHD)红细胞生成素(EPO)抵抗患者pro-hepcidin与炎性反应和铁代谢的关系.方法 40例MHD患者为研究对象,其中20例EPO低反应和20例EPO正常反应.20例健康体检者为对照组.检测参试者的血红细胞计数(RBC)、血红蛋白(Hb)、网织红细胞计数(Ret)、红细胞比容(Hct)、血清铁蛋白(SF)、转铁蛋白(TF)、血清铁和总铁结合力、转铁蛋白饱和度(TSAT)(TSAT=血清铁/总铁结合力)、血清pro-hepcidin、血清超敏C反应蛋白(hs-CRP),并比较组间差异.Pearson相关法分析pro-hepcidin的影响因素.ROC曲线预测pro-hepcidin对EPO抵抗的价值.结果 MHD患者SF、血清pro-hepcidin、hs-CRP显著高于健康对照者(P＜0.01),TF显著低于健康对照者(P＜0.05).EPO抵抗患者血清铁蛋白、血清pro-hepcidin、hs-CRP明显高于反应正常的患者(P＜0.01).Pearson相关分析显示MHD EPO抵抗患者血清pro-hepcidin水平与血清铁蛋白(r=0.843,P=0.000)和hs-CRP(r=0.695,P=0.001)呈正相关.预测EPO抵抗的ROC曲线显示,pro-hepcidin、SF、hs-CRP曲线下面积分别为0.713、0.769和0.958.结论 EPO抵抗与炎性反应和铁代谢相关.血清pro-hepcidin、SF、hs-CRP有可能成为EPO抵抗的标志.     

Acute-phase response predicts erythropoietin resistance in hemodialysis and peritoneal dialysis patients

We defined erythropoietin (EPO) resistance by the ratio of the weekly EPO dose to hematocrit (Hct), yielding a continuously distributed variable (EPO/Hct). EPO resistance is usually attributed to iron or vitamin deficiency, hyperparathyroidism, aluminum toxicity, or inflammation. Activation of the acute-phase response, assessed by the level of the acute-phase C-reactive protein (CRP), correlates strongly with hypoalbuminemia and mortality in both hemodialysis (HD) and peritoneal dialysis (PD) patients. In this cross-sectional study of 92 HD and 36 PD patients, we examined the contribution of parathyroid hormone (PTH) levels, iron indices, aluminum levels, nutritional parameters (normalized protein catabolic rate [PCRn]), dialysis adequacy (Kt/V), and CRP to EPO/Hct. Albumin level serves as a measure of both nutrition and inflammation and was used as another independent variable. Serum albumin level (deltaR2 = 0.129; P < 0.001) and age (deltaR2 = 0.040; P = 0.040) were the best predictors of EPO/Hct in HD patients, and serum albumin (deltaR2 = 0.205; P = 0.002) and ferritin levels (deltaR2 = 0.132; P = 0.015) in PD patients. When albumin was excluded from the analysis, the best predictors of EPO/Hct were CRP (deltaR2 = 0.105; P = 0.003) and ferritin levels (deltaR2 = 0.051; P = 0.023) in HD patients and CRP level (deltaR2 = 0.141; P = 0.024) in PD patients. When both albumin and CRP were excluded from analysis in HD patients, low transferrin levels predicted high EPO/Hct (deltaR2 = 0.070; P = 0.011). EPO/Hct was independent of PTH and aluminum levels, PCRn, and Kt/V. High EPO/Hct occurred in the context of high ferritin and low transferrin levels, the pattern expected in the acute-phase response, not in iron deficiency. In well-dialyzed patients who were iron replete, the acute-phase response was the most important predictor of EPO resistance.     

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.     

Soluble transferrin receptors and reticulocyte hemoglobin concentration in the assessment of iron deficiency in hemodialysis patients

BACKGROUND: Diagnosing iron deficiency in hemodialysis (HD) patients is crucial for correct anemia management. Hypochromic erythrocytes appear to be the best available marker, but they are often unavailable. Transferrin saturation (TSAT) and ferritin are also indicated as reference markers by guidelines. We evaluated the usefulness of soluble transferrin receptor (s-TfR) and reticulocyte hemoglobin concentration (CHr), which have been recently proposed as more sensitive functional iron deficiency indicators. METHODS: A single-center unselected cohort of 39 chronic HD patients underwent a cross-sectional determination of hemoglobin (Hb), hematocrit (Hct), CHr, transferrin, iron, TSAT, ferritin, folate, vitamin B12 and s-TfR. Twenty-nine patients (74.4%) were treated with subcutaneous erythropoietin (EPO) at a dose of 122 +/- 98 U/kg/week and 24 patients (61.5%) were treated with intravenous (i.v.) iron gluconate, 62.5 mg/week. RESULTS: Hb was 11.1 +/- 1.2 g/dL, Hct 34.4 +/- 3.7%, CHr 32.7 +/- 3.8 pg, transferrin 170 +/- 31 mg/dL, iron 60.2 +/- 25.9 mg/dL, TSAT 30 +/- 18%; ferritin 204 +/- 219 ng/mL, folate 4.2 +/- 1.0 mcg/L, vitamin B12 0.58 +/- 0.15 mcg/L, and s-TfR 1.94 +/- 0.83 mg/L. Both TSAT and s-TfR significantly correlated with CHr, but no relationship could be found between s-TfR and TSAT or between s-TfR and ferritin. Dividing the population into two groups based on iron repletion (ferritin >100 ng/mL and TSAT >20%) we found no differences for CHr levels and significantly lower levels of s-TfR in the replete group (s-TfR 1.71 +/- 0.70 vs. 2.29 +/- 0.90 mg/L; p=0.033). Analysis of 2x2 tables demonstrated that 44% of patients with TSAT >20% had elevated (>1.5 mg/L) s-TfR, indicating a possible functional iron deficiency, but covariance analysis showed that TSAT had a better correlation to CHr. CONCLUSIONS: No clear-cut advantages in the use of CHr content and s-TfR levels as single diagnostic tests could be demonstrated by this cross-sectional study. However, our results suggest that the combined use of TSAT <20% and s-TfR >1.5 mg/L (therefore, including all patients with low TSAT, but also patients with high s-TfR despite normal TSAT) could improve functional iron deficiency detection in dialysis patients suspected of having inflammatory conditions.     

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)     

Combined T- and B-cell activation in childhood steroid-sensitive nephrotic syndrome

BACKGROUND: Growing evidence shows that steroid-sensitive nephrotic syndrome (SSNS) is the result of a primary T-cell disturbance and leads to secondary anatomical and functional, however, not to immunological glomerular changes. In addition, immunoglobulin abnormalities in SSNS indicate a role of B-cell involvement. PATIENTS AND METHODS: We therefore analyzed T- and B-cell activation markers in children with SSNS at different stages of the disease including different treatment regimens by measuring the soluble IL-2 receptor (sCD25) and the soluble low-affinity IgE receptor (sCD23), respectively. Seventy-five patients with SSNS (median age 8.0, range 2.5 - 18 years) were studied, 33 in relapse (RL) including 21 patients relapsing during alternate-day steroids (RL-SD). Forty-two patients were studied in remission (RM; 14 off treatment and 28 on alternate-day steroids (RM-AD)) and 22 age-matched children served as controls. RESULTS: Serum concentrations of sCD25 were increased in RL (113.6 +/- 19.5 micromol/l) compared to RM (79.8 +/- 8 micromol/l, p < 0.02) and controls (74.8 +/- 0.9 micromol/l, p < 0.02). Patients with RL-SD did not have elevated sCD25. In relapse, sCD25 was inversely correlated with age (R = -0.36, p < 0.04) and positively correlated with total IgG (R = 0.37, p < 0.04). Urinary excretion of sCD25 was also significantly elevated in RL of SSNS compared to RM and controls (71.2 +/- 11.9 micromol/g creatinine vs. 39.1 +/- 4.8 and 32.0 +/- 4.2 micromol/g, p < 0.05). Serum levels of sCD 23 were significantly elevated in RL (6.22 +/- 0.65 microg/l) compared to RM (3.1 +/- 0.83 microg/l, p < 0.02) and to controls (3.4 +/- 0.93 microg/l). The highest values, however, were found in RL-SD (7.8 +/- 1.7 microg/l) vs. untreated RL (p < 0.007) and RM-AD (p < 0.002). In untreated RL there was a significant correlation of sCD23 and total IgE (R = 0.67, p < 0.02) and in RL-SD with total IgG (R = 0.45, p < 0.05). sCD23 and sCD25 were not correlated with each other. CONCLUSION: These data document parallel abnormalities of both CD23-mediated B as well as CD25-mediated T-cell activation and suggest that SSNS is not solely a disorder of T-cell dysfunction.     

Monitoring the content of reticulocyte hemoglobin (CHr) as the progression of anemia in nondialysis chronic renal failure (CRF) patients

BACKGROUND: We previously showed that the content of reticulocyte hemoglobin (CHr) is a reliable measure of iron status in chronic dialysis patients with erythrocytopoiesis. The CHr was significantly correlated with conventional parameters of iron deficiency in dialysis patients. We attempted to utilize the measurement of CHr levels to monitor iron status and clarify the changes in iron levels that occur as renal anemia progresses in patients with chronic renal failure (CRF). METHODS: We measured CHr, iron parameters, and the intrinsic erythropoietin (EPO) concentration in nondialysis CRF patients who visited our outpatient clinic (n=211). Iron deficiency was defined according to the transferrin saturation (TSAT) and ferritin levels. Conventional red blood cell parameters and CHr levels were measured using an ADVIA120 autoanalyzer (Bayer Medical, USA). RESULTS: The mean CHr value of the nondialysis CRF patients (creatinine clearance less than 70 mL/min) was 32.3 pg, which was not significantly different from that of the dialysis patients. Significant correlations were found between CHr and ferritin levels (r=0.042, p<0.0403) and CHr and TSAT levels (r=0.040, p<0.0157). A positive correlation was observed between the CHr and serum creatinine levels. Nondialysis CRF patients treated with recombinant human EPO (rHuEPO) at a dose of 24,000 U/month exhibited lower CHr levels, compared with those of other patients who received less than 24,000 U/month. CONCLUSION: CHr is an easily measurable and trustworthy marker of iron status in nondialysis CRF patients. Moreover, the CHr level was also sensitive to iron alterations in nondialysis CRF patients receiving rHuEPO treatment, and thus, the CHr value could likely provide useful information regarding the need for iron supplementation.     

Serum levels of immunoglobulins and IgG subclasses in steroid sensitive nephrotic syndrome

Alterations of serum immunoglobulins, especially hypogammaglobulinemia (HG), are a frequent finding in steroid sensitive nephrotic syndrome (SSNS). The exact mechanisms are unclear, especially the persistence of HG into remission. Therefore we studied serum immunoglobulins M, A and G including IgG subclasses 1–4 in 44 children with SSNS; 14 were studied during relapse (RL) and 30 in remission (RM). Data were compared with those of 23 healthy controls. In a subgroup of 23 patients (12 in RM and 11 in RL) we also studied IgG-1 specific antibodies to tetanus toxoid and IgG-2 specific antibodies to pneumococcus antigen. Increased serum concentrations of IgM in RL and reduction of serum IgG in RL and RM were confirmed. During relapse, HG was characterized to result from deficiency of IgG-1–3, whereas in early phases of relapse the reduction was due to low IgG-1 only. In RM the deficiency of IgG-2 persisted for 12 months and correlated strongly with the duration of remission (R=0.60, P<0.0001). IgG-4 levels were not altered in SSNS. In addition, IgG-2 specific antibodies to pneumococcus antigen were significantly reduced only in RL compared to RM (P<0.05). In conclusion, hypogammaglobulinemia of SSNS is characterized by a different constitution of IgG subclasses. In RL a reduction of serum levels of IgG-1–3 occurs, while low concentrations of IgG-2 might be the explanation for HG in remission of SSNS. Received: 3 October 2001 / Revised: 6 December 2001 / Accepted: 7 December 2001     

Limited value of zinc protoporphyrin as a marker of iron status in chronic hemodialysis patients

BACKGROUND: In an attempt to find new parameters able to evaluate the actual iron availability by bone marrow cells, zinc protoporphyrin (ZnPP), a metabolic intermediate generated in the red blood cell by the incorporation of zinc instead of iron, has been proposed. ZnPP is a good marker of iron-deficiency anemia in non-uremic people, as red blood cell ZnPP concentration rises specifically (except for lead intoxication) in this condition. Existing data on ZnPP as a marker of iron deficiency in uremic patients comes mainly from cross sectional studies on chronic hemodialysis and has produced conflicting results. SUBJECTS AND METHODS: Therefore, we prospectively studied 42 HID patients, 28-88 years old, 13-346 months of dialysis age, beginning from a period of maximal iron deficiency, due to the lack of parenteral iron compounds (T0) up to the end of more than one year of follow-up with continuous parenteral iron supplementation (T4). ZnPP, hemoglobin, transferrin saturation and ferritin were serially determined before and after six weeks (T1), four months (T2), seven months (T3) and 14 months (T4) of parenteral iron supplementation at a maintenance dose of 0.5-1 mg/kg/week. RESULTS: In comparison with baseline values (95+/-37 micromol/mol heme) there were no significant changes in ZnPP levels at T1 and T2 despite a continuous increase in both transferrin saturation and ferritin values, while ZnPP significantly decreased at T4 (63+/-37 micromol/mol heme, p<0.001). There was no correlation between ZnPP and both transferrin saturation and ferritin at any time during the study, the same was true for ZnPP and zinc and lead serum concentration, fibrinogen and reactive C protein levels at T1 and T4, respectively. At T4, only 2/10 patients who still showed ZnPP levels >80 micromol/mol heme had absolute or functional iron deficiency, when the percentage of hypochromic red cells were measured. CONCLUSION: We conclude that ZnPP untimely parallels a change in iron balance in only a proportion of uremic people, in as much as confounding factors, such as chronic inflammation and uremia in itself may obscure its relationship with iron status. Therefore, ZnPP cannot be assumed to be a first-line diagnostic marker of iron balance in uremic patients.     

Nutritional-inflammation status and resistance to erythropoietin therapy in haemodialysis patients.

BACKGROUND: Chronic kidney disease patients who are resistant to erythropoietin (EPO) treatment may suffer from malnutrition and/or inflammation. METHODS: In a cross-sectional study of haemodialysis patients, we investigated the relationship between the natural logarithm of the weekly EPO dose normalized for post-dialysis body weight and outcome measures of nutrition and/or inflammation [BMI, albumin and C reactive protein (CRP)] by means of multiple linear regression analysis. On the basis of the decile distribution of weekly EPO doses, we also evaluated four groups of patients: untreated, hyper-responders, normo-responders and hypo-responders. RESULTS: Six hundred and seventy-seven adult haemodialysis patients were recruited from five Italian centres. BMI and albumin were lower in the hypo-responders than in the other groups (21.3+/-3.8 vs 24.4+/-4.7 kg/m(2), P<0.001; and 3.8+/-0.6 vs 4.1+/-0.4 g/dl, P<0.001), whereas the median CRP level was higher (1.9 vs 0.8 mg/dl, P = 0.004). The median weekly EPO dose ranged from 30 IU/kg/week in the hyper-responsive group to 263 IU/kg/week in the hypo-responsive group. Transferrin saturation linearly decreased from the hyper- to hypo-responsive group (37+/-15 to 25+/-10%, P = 0.003), without any differences in transferrin levels. Ferritin levels were lower in the hypo-responsive than in the other patients (median 318 vs 445 ng/ml, P = 0.01). At multiple linear regression analysis, haemoglobin, BMI, albumin, CRP and serum iron levels were independently associated with the natural logarithm of the weekly EPO dose (R(2) = 0.22). CONCLUSIONS: Our findings support a clear association between EPO responsiveness and nutritional and inflammation variables in haemodialysis patients; iron deficiency is still a major cause of hypo-responsiveness.     

The effect of i.v. iron alone or in combination with low-dose erythropoietin in the rapid correction of anemia of chronic renal failure in the predialysis period

BACKGROUND: It is now more and more evident that anemia of predialysis chronic renal failure (CRF) should be actively treated, since long-standing anemia may cause irremediable damage to the heart. The most common form of treatment of this anemia is subcutaneous erythropoietin (EPO). iron (Fe) deficiency can also contribute to anemia in predialysis CRF, and intravenous iron (i.v. Fe) can frequently improve it. It is possible, therefore, that the combination of EPO and i.v. Fe may have an additive effect, and cause a rapid improvement in anemia with relatively small doses of EPO. PURPOSE: The purpose of this study was an initial study: to assess the ability of a combination of low-dose EPO and i.v. Fe, given weekly for 5 doses, to correct the anemia of predialysis CRF patients compared to the use of i.v. Fe alone in a randomized study. In the follow-up study: to assess the ability of the maintenance of adequate iron stores for one year to achieve and maintain the target Hct of 35% with the minimum dose of EPO. Initial study: METHOD: Ninety predialysis CRF patients (creatinine clearance 10-40 ml/min/1.73 m2 received either: Group A (45 patients): 200 mg i.v. Fe as Fe sucrose (Venofer, Vifor Int.) once per week for 5 doses in combination with 2,000 international units (IU) EPO (Eprex, Cilag-Janssen), subcutaneously given simultaneously also for 5 doses. Group B (45 patients): the same dose of i.v. Fe as in Group A but without EPO. RESULTS: The mean increase in hematocrit (Hct) and hemoglobin (Hb) by one week after the last dose was greater in group A, 4.54 +/- 2.64% (p < 0.01) and 1.37 +/- 0.84 g% (p < 0.01), respectively, than in Group B, 2.74 +/- 2.72% (p < 0.05) and 0.91 +/- 0.78 g% (p < 0.05), respectively. 80% of those in Group A had an increase in Hct of 3 vol% or more compared to 48.9% in Group B (p < 0.01). 40% of those in Group A reached the target Hct of 35% compared to 28.9% in Group B (p > 0.05). Follow-up study: During a 12-month follow-up period, enough i.v. iron was given to maintain the Hct at 35%, while keeping the serum ferritin at < 400 ug/l and % Fe Sat at < 40%. If the i.v. Fe alone was not capable of maintaining the target Hct, EPO was given in increasing doses. Eighteen patients required dialysis. Of the 72 patients who did not require dialysis, 24 (33.3%) maintained the target Hct with i.v. Fe alone, without EPO. All the remaining 48 patients (66.7%) continued to receive EPO in addition to the i.v. Fe, and 47 achieved and maintained the target Hct with a mean EPO dose of 2,979 +/- 1,326 IU/week. CONCLUSION: The combination of low-dose EPO and i.v. Fe had a rapid and additive effect on the correction of anemia in CRF predialysis patients. Maintaining adequate iron stores with i.v. Fe during a subsequent maintenance phase allowed the target Hct of 35% to be reached and maintained with low-dose EPO in two-thirds of the predialysis patients and with no EPO at all in one-third.     

Inflammation and pruritus in haemodialysis patients.

BACKGROUND: Pruritus is a common symptom among patients on haemodialysis (HD). We studied 68 HD patients to assess the role of iron deficiency, anaemia, inflammation and other common serum and dialysis parameters in pruritus. METHODS: The patients were questioned about the occurrence of pruritus at home, quantified according to frequency ('never', 'occasionally' and 'every day') and intensity ('absent', 'moderate' and 'severe'). The blood and serum variables considered were: haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, hypochromic red blood cells (RBC), hyperchromic RBC, microcytic RBC, macrocytic RBC, reticulocytes, iron, ferritin, transferrin, transferrin saturation, C-reactive protein (CRP), urea, creatinine, calcium, phosphorus, albumin, total protein and glucose. We also analysed Kt/V, age and time on HD treatment. Patients were divided into 3 groups according to the frequency or intensity of their pruritus, and we analysed and compared the variables between the 3 groups. RESULTS: Half (50%) of the patients reported never having pruritus, 32.4% occasionally and 17.6% every day. Pruritus was moderate in 41.2% of them and severe in 8.8%. None of the parameters considered revealed any statistically relevant differences between the three pruritus frequency groups, except for mean serum transferrin level (mg/dl) ('never'=268+/-64 vs 'occasionally'=244+/-40 vs 'every day'=217+/-56, P<0.05). As for the intensity of the symptom, mean serum transferrin (268+/-64 vs 247+/-39 vs 174+/-31, P<0.001) and median ferritin levels (mg/dl) (83 (11-420) vs 98 (11-1121) vs 293 (111-471), P<0.05) showed statistically significant differences between the 3 groups, as did albumin levels (g/dl) (4.3+/-0.4 vs 4.2+/-0.4 vs 3.7+/-0.4, P<0.05). Median CRP values (mg/dl) tended to be higher in patients with more frequent (0.4 (0.3-5.5) vs 0.7 (0.3-11.4) vs 0.9 (0.3-13.5)) and more severe pruritus (0.4 (0.3-5.5) vs 0.7 (0.3-4.0) vs 2.1 (0.3-13.5)), but those differences were not statistically significant. CONCLUSIONS: Iron deficiency and anaemia seem to play no part in HD-related pruritus, whereas lower serum transferrin and albumin levels and higher ferritin values are consistent with the possible role of inflammation in the development and severity of pruritus.     

Serum ferritin levels are increased in patients with glomerular diseases and proteinuria.

BACKGROUND: Ferritin is a high molecular weight protein which reflects body iron stores, but may also rise in the case of an acute phase response. Recently, ferritin has been identified as a predictive factor in the development and progression of atherosclerosis. This is the first report on serum ferritin levels in patients with proteinuria. METHODS: We have analysed the data of 142 male patients with a glomerular disease, and proteinuria exceeding 1 g/day. In all patients, we measured various parameters related to proteinuria, serum ferritin and serum iron. Serum beta2-microglobulin and the Modification of Diet in Renal Disease (MDRD) equation were used as measures of the glomerular filtration rate (GFR). RESULTS: Mean age (+/-SD) was 46+/-15 years, MDRD-GFR 57+/-25 ml/min/1.73 m2 and median proteinuria 8.0 g/day [interquartile range (IQR) 3.6-13]. Serum albumin (29+/-9 g/l) and transferrin levels (1.7+/-0.5 g/l) were low, and cholesterol levels were elevated (median 7.3, IQR 5.9-9.5 mmol/l). Median serum ferritin was 148 microg/l (IQR 89-282), and exceeded 280 microg/l, the upper limit of normal, in 36 patients (25%). Elevated serum ferritin levels could not be explained by an acute phase response as determined by C-reactive protein, or haemochromatosis (DNA analysis). Regression analysis showed an independent relationship between ferritin levels and serum cholesterol, GFR and serum transferrin. CONCLUSIONS: Serum ferritin levels are elevated in patients with overt proteinuria. The independent negative relationship between serum ferritin and transferrin points to a specific process and suggests that increased production of ferritin may compensate for the loss of the iron-binding protein transferrin, thus reducing the amount of free iron. Further studies are needed to elucidate the role of ferritin in patients with proteinuria, especially because of the suggested association between ferritin and atherosclerosis.     

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.     

Urinary albumin, transferrin and iron excretion in diabetic patients.

The present study was undertaken to determine urinary and serum iron, transferrin and albumin levels in diabetic patients with varying amounts of proteinuria. A highly significant correlation was found between urinary albumin and transferrin excretion over a wide range of urinary albumin excretion (0.005 to 18 g/g creatinine) (r = 0.972). The urine/serum ratio of transferrin and albumin were identical, documenting a similar glomerular leak and tubule handling for these two proteins. In contrast to the above correlation between transferrin and albumin, there was no correlation between iron and either of these proteins until nephrotic range proteinuria had occurred, and even at that time the correlation was much weaker than that found between the proteins (r = 0.680). Urinary iron excretion increased early in the course of diabetic renal disease, being increased in 3 of 11 patients without proteinuria and in 8 of 10 patients with mild proteinuria. All patients with nephrotic range proteinuria had markedly increased urinary iron excretion (150 +/- 166 micrograms/g creatinine vs. 6.4 +/- 0.7 micrograms/g creatinine in controls) and decreased serum iron levels (592 +/- 189 micrograms/liter vs. 979 +/- 394 micrograms/liter in the control group). The iron/transferrin ratio in urine was consistently greater than the iron/transferrin ratio in plasma at all stages of proteinuria. In patients with both subnephrotic and nephrotic range proteinuria, approximately 35 to 40 micrograms Fe/g creatinine was present in the urine with an excess of transferrin. In conclusion, urinary iron excretion is increased early in the course of diabetic renal disease.(ABSTRACT TRUNCATED AT 250 WORDS)     

Is hemojuvelin a possible new player in iron metabolism in hemodialysis patients?

Introduction

Hemojuvelin (HJV) is highly expressed in the liver, skeletal muscles, and heart, seems to play a role in iron absorption and release from cells, and has anti-inflammatory properties. Moreover, HJV plays an essential role in the regulation of hepcidin expression, specifically in the iron-sensing pathway. Hepcidin has emerged as a key regulator of iron homeostasis. In this study we tested for the first time the hypothesis that HJV is related to iron metabolism in hemodialysis (HD) patients.

Methods

Iron status, complete blood count, and serum creatinine, albumin, and lipids were assessed, using standard laboratory methods. Serum levels of soluble transferrin receptor (sTFR), high-sensitivity CRP, IL-6, hepcidin, and HJV were measured using commercially available kits.

Results

Serum HJV, hepcidin, ferritin, IL-6, hsCRP, and serum creatinine were significantly higher (all P?<?0.001), whereas serum iron, sTFR, transferrin, hemoglobin, and erythrocyte count were significantly lower in HD patients, compared to healthy volunteers (all P?<?0.001). In univariate analysis, HJV was strongly correlated (P?<?0.001) with ferritin, transferrin saturation, and TIBC, as well as with hsCRP, hepcidin, Kt/V (P?<?0.01) and residual renal function, the presence of diabetes, APKD, and coronary heart disease. Predictors of HJV level in multiple regression analysis were ferritin (beta value was 0.50, P?=?0.00004) and transferrin saturation (beta value was 0.47, P?=?0.0002), explaining 81% of the HJV variations.

Conclusions

Serum HJV is elevated in HD patients and related predominantly to kidney function and iron metabolism. However, HJV is probably not correlated to inflammation. HJV appears to be a new player in iron metabolism in these patients.     

Iron deficiency is a common cause of anemia in chronic kidney disease and can often be corrected with intravenous iron

BACKGROUND: There is some epidemiological and clinical evidence that the anemia seen in chronic kidney disease (CKD) in patients not on dialysis could be due to a significant extent to iron deficiency, and that adequate iron replacement could cause a marked improvement in the anemia even without the use of erythropoietin (EPO). The purpose of this work was to study the effects of intravenous (i.v.) iron administration (ferric gluconate - Ferrlecit) on hemoglobin (Hb) of patients with CKD. METHODS: Forty-seven consecutive patients with CKD with Hb <12 g/dL in whom no underlying cause for the anemia could be found underwent sternal bone marrow biopsy and had their red cell and blood iron parameters measured. They then received 250 mg of ferric gluconate (Ferrlecit) intravenously twice monthly for 3 months, and had their blood parameters measured 1 month later. No patient received erythropoietin (EPO). RESULTS: Forty-six patients had no evidence of any iron deposits in the bone marrow - consistent with the presence of severe iron deficiency. The mean serum ferritin and %transferrin saturation prior to treatment were 235.9 +/- 54.3 ug/L and 13.5 +/- 4.1%, respectively, and both increased significantly with the iron treatment. Mean Hb increased from 10.16 +/- 1.32 to 11.96 +/- 1.52 g/dL, an increase of 1.80 +/- 1.72 g/dL (p<0.01). Twenty-six patients (55.3%) reached the target Hb of 12 g/dL. Ten patients (21.3%) had an increase of 0.1-0.9 g/dL, nine patients (19.1%) had an increase of 1-1.9 g/dL and 23 patients (48.9%) had an increase of >or= 2 g/dL. CONCLUSIONS: Iron deficiency is frequently seen in anemic CKD patients not on dialysis and its correction with i.v. iron will often cause a marked increase in the Hb level, and the achievement of the target Hb of 12 g/dL even without EPO.     

Transferrin synthesis is increased in nephrotic patients insufficiently to replace urinary losses

The urinary loss of transferrin is sufficient to reduce plasma transferrin concentrations in the nephrotic syndrome. Hypotransferrinemia may lead to iron loss and microcytic anemia. The mechanism responsible for the hypotransferrinemia in the nephrotic syndrome is, however, unknown. In the present study, synthesis rate of transferrin was measured in vivo in nephrotic patients (n = 7) compared with control subjects (n = 6) using L-[1-(13)C]-valine. Plasma transferrin and iron concentration in the patients were significantly lower than in control subjects (transferrin, 1.39 +/- 0.08 versus 2.57 +/- 0.11 g/L, P < 0.0001; iron, 10.2 +/- 0.8 versus 21.1 +/- 4.5 micromol/L, P = 0.02). Furthermore, albuminuria correlated with transferrinuria (r(2) = 0.901, P = 0.001). The absolute synthesis rate of transferrin was increased in the patients (10.0 +/- 1.1 versus 7.4 +/- 0.7 mg/kg per d, P = 0.07), although this value failed to achieve significance. C-reactive protein, plasma iron, and proteinuria did not correlate with transferrin synthesis. In contrast, transferrin synthesis correlated with albumin synthesis (r(2) = 0.648, P = 0.03; n = 7). The present study indicates that increased transferrin synthesis occurs in nephrotic patients but is insufficient to compensate for urinary losses. Because, overall, no significant relationship was found between transferrin synthesis and either C-reactive protein or iron, it is unlikely that inflammation suppresses or that iron deficiency stimulates increased transferrin synthesis in these patients. The correlation between transferrin synthesis and albumin synthesis suggests that transferrin synthesis is a component of a general response in hepatic protein synthesis in the nephrotic syndrome. This suggests that a therapeutic approach to maximize plasma transferrin concentrations in nephrotic patients should be aimed primarily at reducing urinary protein excretion.