Spontaneous variability of pre-dialysis concentrations of uremic toxins over time in stable hemodialysis patients.

BACKGROUND AND AIM: Numerous outcome studies and interventional trials in hemodialysis (HD) patients are based on uremic toxin concentrations determined at one single or a limited number of time points. The reliability of these studies however entirely depends on how representative these cross-sectional concentrations are. We therefore investigated the variability of predialysis concentrations of uremic toxins over time. METHODS: Prospectively collected predialysis serum samples of the midweek session of week 0, 1, 2, 3, 4, 8, 12, and 16 were analyzed for a panel of uremic toxins in stable chronic HD patients (N = 18) while maintaining dialyzer type and dialysis mode during the study period. RESULTS: Concentrations of the analyzed uremic toxins varied substantially between individuals, but also within stable HD patients (intra-patient variability). For urea, creatinine, beta-2-microglobulin, and some protein-bound uremic toxins, Intra-class Correlation Coefficient (ICC) was higher than 0.7. However, for phosphorus, uric acid, symmetric and asymmetric dimethylarginine, and the protein-bound toxins hippuric acid and indoxyl sulfate, ICC values were below 0.7, implying a concentration variability within the individual patient even exceeding 65% of the observed inter-patient variability. CONCLUSION: Intra-patient variability may affect the interpretation of the association between a single concentration of certain uremic toxins and outcomes. When performing future outcome and interventional studies with uremic toxins other than described here, one should quantify their intra-patient variability and take into account that for solutes with a large intra-patient variability associations could be missed.

Follow a recipe to prescribe phosphate during hemodialysis. / Receta para prescribir fósforo durante hemodiálisis.

The addition of phosphorus (P) to the dialysate (LD) in the form of enema Casen® is common practice in patients with hypophosphatemia. The estimation of the amount to be used and the identification of the problems that may can occur are not well defined. As a result of our work we propose a practical approach of how to proceed to increase phosphate concentration in the hemodialysate. We present a reasoned formula to calculate how much enema has to be added and the problems that may arise.

Electrolytes-Enriched Hemodiafiltration Solutions for Continuous Renal Replacement Therapy in Acute Kidney Injury: A Crossover Study.

AIMS: To evaluate the capability of an electrolytes-enriched solution to prevent metabolic disorders during continuous veno-venous hemodiafiltration (CVVHDF). METHODS: Serum biochemistry and clinical tolerance were compared during CVVHDF treatments with an electrolyte-enriched (Phoxilium) or standard solutions in 10 acute renal failure patients. RESULTS: As compared to standard fluids, serum potassium and phosphate levels were maintained in the normal range with Phoxilium without any supplementation but total serum calcium levels were significantly lower. Bicarbonatemia was slightly higher (24-26 vs. 21.5-24.5 mmol/l, p < 0.05) with conventional solutions and was associated with a significant increased level of pH (>7.44). Despite the absence of glucose in the Phoxilium solution, blood glucose levels and glucose supplementation were similar between treatments. Clinical tolerance and efficiency of CVVHDF sessions were comparable. CONCLUSION: Phoxilium effectively prevented hypophosphatemia and hypokalemia during CVVHDF. It was, however, associated with a slight metabolic acidosis and hypocalcemia compared with conventional solutions.

[Online hemodiafiltration in children and hypoparathyroidism: a single-centre series of cases]. / Hémodiafiltration online et hypoparathyroïdie chez l'enfant : une série de cas monocentrique.

BACKGROUND: Due to technical requirements and cost, hemodiafiltration (HDF) is not widely used in pediatrics. We have been using online HDF (oHDF) since 2009 and we observed low parathyroid hormone (PTH) levels despite the accurate management of CKD-MBD. METHODS: We reviewed the medical charts and parameters of mineral metabolism assessed on a before/after session basis in the 6 children undergoing chronic oHDF in our centre. RESULTS: We observed low (<80pg/mL) PTH levels in all 6 patients and very low (<45pg/mL) PTH levels in 5, two of them presenting with pathological fractures. These low PTH levels were reversed after decreasing calcium concentration to 1.25 mmol/L in the dialysate, suggesting that high-efficiency oHDF may expose children to calcium during sessions in a too important amount when using 1.5 mmol/L dialysates. Last, C-terminal FGF23 levels before sessions were relatively low (<1600RU/mL), with a 32% clearance by oHDF. CONCLUSION: PTH levels should be closely monitored in pediatric oHDF and solutions with a calcium concentration of 1.25 mmol/L should be used as first line in these patients.

Calciphylaxis in dialysis patients, a severe disease poorly responding to therapies: report of 4 cases.

Calciphylaxis or calciphic uremic arteriolopathy (CUA) is a rare syndrome characterized by the deposition of calcium within the walls of small and medium size vessels in the dermis and in the subcutaneous tissue. The disease mainly affects patients with end-stage renal disease. We report here our experience with 4 cases of calciphylaxis in dialysis patients. The main predisposing factor observed in our 4 patients was warfarin use (2 patients, 50%), while local traumas and diabetes were respectively present in only one patient. None of our patients was obese. Lower legs were the most frequently involved site of CUA (3/4 patients, 75%). In our experience biopsy was crucial to achieve a correct diagnosis and did not cause aggravation of the ulcers. Therapeutic approach was multimodal: mainly hyperbaric oxygen therapy, cinacalcet and sodium thiosulphate. Although many recent case reports have shown exceptional results and healing with the use of sodium thiosulphate, we did not experience any change in the poor prognosis of our patients with the use of this drug, at a dosage of 5 g thrice weekly endovenously.

Pre-emptive replacement of water treatment components improves responsiveness to erythropoiesis-stimulating agents in maintenance haemodialysis patients: a quality improvement report.

Hypo-responsiveness to erythropoiesis-stimulating agents (ESAs) has been associated with increased mortality. We examined the effect of water treatment component replacement on declining ESA responsiveness in the absence of chemical or microbiological standards failure. Pre-emptive renewal of the water treatment system supplying 802 standard-flux haemodialysis patients resulted in a significant rise in haemoglobin from (mean ± SD) 12.1 ± 1.2 to 12.3 ± 1.0 g/dl (p < 0.0001), accompanied by a significant decrease in prescribed dose of darbepoetin alfa from 47.9 ± 27.3 to 44.7 ± 27.6 µg/week (p < 0.0001). ESA responsiveness improved significantly from 0.060 ± 0.041 to 0.055 ± 0.040 µg/kg/g · dl(-1) (p < 0.0001) and the number of patients no longer requiring ESA therapy increased threefold. These benefits were derived in the absence of haemolysis or significant changes in water quality. Renewal of water system components should be conducted even in the absence of proven microbiological and chemical failure.

Physiologic volume of phosphorus during hemodialysis: predictions from a pseudo one-compartment model.

The kinetics of plasma phosphorus concentrations during hemodialysis (HD) are complex and cannot be described by conventional one- or two-compartment kinetic models. It has recently been shown by others that the physiologic (or apparent distribution) volume for phosphorus (Vr-P) increases with increasing treatment time and shows a large variation among patients treated by thrice weekly and daily HD. Here, we describe the dependence of Vr-P on treatment time and predialysis plasma phosphorus concentration as predicted by a novel pseudo one-compartment model. The kinetics of plasma phosphorus during conventional and six times per week daily HD were simulated as a function of treatment time per session for various dialyzer phosphate clearances and patient-specific phosphorus mobilization clearances (K(M)). Vr-P normalized to extracellular volume from these simulations were reported and compared with previously published empirical findings. Simulated results were relatively independent of dialyzer phosphate clearance and treatment frequency. In contrast, Vr-P was strongly dependent on treatment time per session; the increase in Vr-P with treatment time was larger for higher values of K(M). Vr-P was inversely dependent on predialysis plasma phosphorus concentration. There was significant variation among predicted Vr-P values, depending largely on the value of K(M). We conclude that a pseudo one-compartment model can describe the empirical dependence of the physiologic volume of phosphorus on treatment time and predialysis plasma phosphorus concentration. Further, the variation in physiologic volume of phosphorus among HD patients is largely due to differences in patient-specific phosphorus mobilization clearance.

Phosphate enrichment of dialysate for use in standard and extended haemodialysis.

BACKGROUND/AIMS: Intensive haemodialysis (HD) sometimes causes hypophosphataemia, but phosphate-containing dialysate is not readily available. We examined the effectiveness of extemporaneously producing a phosphate-rich dialysate for use in HD. METHODS: Incremental volumes of Fleet® were added to acid concentrate and predicted to deliver dialysate phosphate concentrations of 0.19-1.1 mmol/l, following mixture with ultrapure water and base concentrate by the HD machine. RESULTS: The achieved concentrations were close to predicted values (p = 0.77) and remained stable throughout an 8-hour 'treatment' time (p = 0.99). The dialysate phosphate concentration had a linear relationship with the Fleet® volume added, defined by the regression equation y = 172.79 x - 1.47 (R(2) = 0.99, r = 0.99, p = 0.003). The dialysate pH, calcium, magnesium and bicarbonate concentrations did not change over the study period (p = 0.28-0.99). Microscopic analysis under polarised light showed no evidence of crystal formation. CONCLUSION: The study validates a simple, reliable and cost-effective protocol for phosphate supplementation in conventional and extended HD.

Effectiveness and cost-efficacy of phosphate binders in hemodialysis.

OBJECTIVES: Worldwide, incidence rates of chronic renal insufficiency have clearly increased over the past decade, especially in people of older age. Hyperphosphatemia is the strongest independent risk factor for mortality in renal patients. In order to reduce serum phosphate concentrations to recommended values, phosphate binders (P binders) are used to bind ingested phosphate in the digestive tract. Besides the traditional therapies with calcium and aluminium salts, sevelamer and lanthanum represent recent developments on the market. The purpose of the present health technology assessment (HTA) report was to compare the effectiveness and safety of different P binders in patients with chronic renal insufficiency. METHODS: Based on a systematic literature search followed by a two-part selection process with predefined criteria 18 publications were included in the assessment. RESULTS: All P binders effectively controlled serum phosphate, calcium and parathyroid hormone concentrations. The numbers of hypercalcemic episodes were higher when using calcium-containing P binders compared to sevelamer and lanthanum. Regarding mortality rate, cardiovascular calcification and bone metabolism no definite conclusions could be drawn; however, sevelamer seemed to be more effective than calcium in certain patient subgroups, such as older patients and patients with preexisting arterial calcification. CONCLUSIONS: From a medical point of view, sevelamer showed superiority over calcium-containing P binders at least for special indications.

Voltammetric determination of Se(IV) and Se(VI) in saline samples--studies with seawater, hydrothermal and hemodialysis fluids.

Determination of Se(IV) and Se(VI) in high saline media was investigated by cathodic stripping voltammetry (CSV). The voltammetric method was applied to assay selenium in seawater, hydrothermal and hemodialysis fluids. The influence of ionic strength on selenium determination is discussed. The CSV method was based on the co-electrodeposition of Se(IV) with Cu(II) ions and Se(VI) determined by difference after sample UV-irradiation for photolytic selenium reduction. UV-irradiation was also used as sample pre-treatment for organic matter decomposition. Detection limit of 0.030 microg L(-1) (240 s deposition time) and relative standard deviation (RSD) of 6.19% (n=5) for 5.0 microg L(-1) of Se(IV) were calculated. Linear calibration range for selenium was observed from 1.0 to 100.0 microg L(-1). Concerning the pre-treatment step, best results were obtained by using 60 min UV-irradiation interval in H(2)O(2)/HCl medium. Se(VI) was reduced to the Se(IV) electroactive species with recoveries between 91.7% and 112.9%. Interferents were also investigated.

Continuous venovenous hemodiafiltration trace element clearance in pediatric patients: a case series.

Continuous renal replacement therapy (CRRT) is used to treat critically ill children with acute kidney injury. The effect of CRRT on trace element clearance is poorly characterized. The purpose of this study was to quantify the transmembrane clearance of chromium, copper, manganese, selenium and zinc during continuous venovenous hemodiafiltration (CVVHDF). The transmembrane clearance of trace elements was assessed prospectively in five critically ill children receiving CVVHDF at the pediatric intensive care unit of a tertiary care university hospital. Pre-filter blood and effluent samples were measured for trace element concentrations. Transmembrane clearance of trace elements was calculated, and daily loss of each trace element was determined. Daily trace element loss via CVVHDF was compared with daily standard supplementation of trace elements in pediatric parenteral nutrition. Five patients (age range 23 months to 15 years) with a body weight range of 10.5-53 kg completed the study. The median transmembrane clearance of chromium, copper, manganese, selenium and zinc during CVVHDF was calculated as 0 ml, 0.59 ml, 2.48 ml, 1.22 ml, and 1.90 ml, respectively, per 1.73 m(2) body surface area per minute. The calculated CVVHDF losses were substantially smaller than the daily parenteral supplementation for all trace elements.

Enhanced clearance of highly protein-bound drugs by albumin-supplemented dialysate during modeled continuous hemodialysis.

BACKGROUND: In 2006, there were 16 796 toxic exposures attributed to valproic acid (VPA), carbamazepine (CBZ) and phenytoin (PHT) reported to the US Toxic Exposure Surveillance System. Of these, 30% (5046) were treated in a health care facility with 12 cases resulting in death. These drugs are highly protein bound and poorly dialyzable; however, it has been suggested that albumin-supplemented dialysate may enhance dialytic clearance. We investigated whether the addition of albumin to dialysate affects dialytic clearance of VPA, CBZ and PHT. METHODS: VPA, CBZ and PHT were added to a bovine blood-based in vitro continuous hemodialysis circuit, which included a polysulfone or an AN69 hemodialyzer. VPA, CBZ and PHT clearances were calculated from spent dialysate and pre-dialyzer plasma concentrations. VPA, CBZ and PHT clearances with control (albumin-free) dialysate were compared to clearances achieved with 2.5% or 5% human albumin-containing dialysate. The influences of blood flow (180 and 270 mL/min) and dialysate flow (1, 2 and 4 L/h) on dialysis clearance were also assessed. RESULTS: The addition of 2.5% albumin to dialysate significantly enhanced dialytic clearance of VPA and CBZ, but not PHT. Use of 5% albumin dialysate further increased VPA and CBZ clearance. Overall, drug clearance was related directly to dialysate flow but independent of blood flow. CONCLUSION: Continuous hemodialysis with albumin-supplemented dialysate significantly enhanced VPA and CBZ, but not PHT, clearance compared to control dialysate. Continuous hemodialysis with albumin-supplemented dialysate may be a promising therapy to enhance dialytic clearance of selected highly protein-bound drugs.

[Technical advances in haemodialysis]. / Nouveautés techniques en hémodialyse.

Survival improvement of our haemodialysis patients is partly due to technologic improvement of the dialysis therapy. High permeability membranes and bicarbonate dialysate were the most relevant of past decades. What are the present technologic innovations that will provide clinical benefit? Acetate-free biofiltration, biofeedback systems, better haemodiafiltration techniques and techniques with adsorption could be part of them.

Citrate anticoagulation protocol for slow extended hemodialysis with the Genius dialysis system in acute renal failure.

BACKGROUND: The Genius dialysis system is increasingly used as an intermittent hemodialysis device in the setting of acute renal failure. Slow extended hemodialysis is preferred in the case of critical ill patients. In this study we established a safe and feasible citrate anticoagulation protocol for slow extended hemodialysis (SLED) with the Genius system. METHODS: We compared six anticoagulation protocols using SLED in 34 critically ill patients with acute renal failure. One group (A) received only citrate anticoagulation. Four groups (B - D) were treated with citrate and different additional systemic anticoagulation. Patients in the last group (F) were anticoagulated with heparin and were free of citrate anticoagulation. The total number of treatments was 103. A 4% sodium citrate solution was infused into the arterial line of the dialysis device for citrate anticoagulation. The dialysis solution contained one mmol/L of calcium. No additional calcium supplementation was done. We monitored electrolyte, acid-base and cardiovascular status prospectively. RESULTS: Hemodialysis was well tolerated hemodynamically. Electrolytes remained stable throughout hemodialysis in all groups. The decrease in ionized and total calcium was within the expected, clinically acceptable range. Bicarbonate and pH levels increased during dialysis, especially if citrate was used. CONCLUSIONS: Slow extended Genius hemodialysis with citrate is well tolerated and offers a safe and effective alternative to systemic anticoagulation.

Low-calcium dialysate improves mineral metabolism in hemodialysis patients.

BACKGROUND: The Kidney Disease Outcomes Quality Initiative (K/DOQI) Guidelines for Bone Metabolism and Disease in Chronic Kidney Disease recommend 1.25 mmol/l Ca dialysate for both hemodialysis and peritoneal dialysis, while 1.5 mmol/l Ca dialysate has been used in our dialysis center. METHODS: Therefore, we switched the dialysate calcium concentration from 1.5 - 1.25 mmol/l and observed the effects on serum calcium (S-Ca), phosphorus (S-P), 1-84 parathyroid hormone (whole PTH, w-PTH), bone-specific alkaline phosphatase (BAP), and tartrate-resistant acid phosphatase isoform 5b (TRACP-5b) for 6 months in 58 hemodialysis patients. Prescription of active vitamin D (VD) metabolites and Ca carbonate was increased in response to the changes in laboratory data. RESULTS: Decrease of S-Ca was evident at 2 weeks and S-Ca remained low for 6 months. Transient elevation of S-P, which might be caused by stimulated bone resorption, was observed after the switch. In patients with low PTH (w-PTH less than 90 pg/ml before the switch), continuous increase of w-PTH, BAP, and TRACP-5b was observed. This appeared to be a favorable response because the risk ofadynamic bone disease was high in this group of patients. On the other hand, acute elevation of the 3 parameters was well-controlled in patients with moderate and high PTH (w-PTH from 90 - 180 pg/ml, w-PTH more than 180 pg/ml, respectively) by increased dosage of active VD. CONCLUSION: These results demonstrate that 1.25 mmol/l Ca dialysate improved mineral metabolism by lowering S-Ca and releasing oversuppression of PTH. Our data also suggest that appropriate use of active VD could prevent acute rise of PTH.

Effects on inflammatory and nutritional markers of haemodiafiltration with online regeneration of ultrafiltrate (HFR) vs online haemodiafiltration: a cross-over randomized multicentre trial.

BACKGROUND: HFR [double chamber haemodiafiltration (HDF) with reinfusion of regenerated ultrafiltrate] is a novel dialytic method which combines the processes of diffusion, convection and adsorbance. In this technique an adsorbent cartridge of resin and charcoal may regenerate the ultrafiltrate suggesting its use as an endogenous substitution fluid. The aim of this multicentre randomized cross-over study was to compare HFR to online HDF in terms of inflammatory and nutritional parameters. METHODS: After a 1 month run-in period of standard bicarbonate dialysis (HD) with a synthetic membrane, 25 chronic dialytic patients were randomized (A-B or B-A) to be treated by HFR (A) with a two-chamber filter (SG 8 Plus - high permeability Polysulphone HF 0.7 m2 + SMC 1.95 sqm; Bellco, Mirandola, Italy) or by online sterile bicarbonate HDF. Each study period of 4 months was separated by 1 month of HD and the entire length of the study was 10 months. CRP levels were measured by a highly sensitive nephelometric assay (Dade, Behring) with a sensitivity of 0.1 microg/ml. Cytokine concentrations were determined by EIA [Interleukin (IL) 6, Biosource, USA and IL-10 Bender MED-Systems, Vienna]. The sensitivity thresholds were < 5 pg/ml for IL-6 and < 8 pg/ml for IL-10. Serum leptin was determined with a ELISA method (Biosource, USA). All parameters were determined monthly in patients starting a midweek dialytic session. RESULTS: Plasma CRP and IL-6 were significantly reduced during the 4 months of HFR and HDF: CRP from 8.0 +/- 3.2 to 5.6 +/- 3.4 mg/l with HFR (P < 0.05) and from 9.4 +/- 4.3 to 5.9 +/- 3.9 mg/l with HDF (P < 0.05). IL-6 decreased from 14.8 +/- 6.3 to 10.1 +/- 3.2 with HFR (P < 0.02) and from 12.1 +/- 4.2 to 9.6 +/- 3.7 with HDF (P = ns) with a percentage decrease after 4 months of 32% with HFR vs 21% with HDF. During the 1 month wash-out period with HD, CRP increased from 5.7 +/- 3.6 to 8.7 +/- 3.9 mg/l (P < 0.01) and IL-6 from 10 +/- 3.4 to 13.5 +/- 5.2 pg/ml (P < 0.01). A significant increase in IL-10 was detected either in HFR (from 4.8 +/- 2.1 to 6.89 +/- 1.7 pg/ml) and in HDF (from 3.3 +/- 1.7 to 8.95 +/- 4.3 pg/ml; P < 0.05) after 4 months. No significant variation in serum leptin levels were observed during the study. CRP and IL-6 were highly correlated (r = 0.54; P < 0.001) as was serum albumin and prealbumin (r = 0.39; P < 0.001). Serum albumin was negatively correlated with CRP (r = -0.26; P < 0.01) and IL-6 (r = -0.19; P < 0.05); serum prealbumin was correlated with IL-6 (r = 0.37; P < 0.001) and with CRP (r = 0.24; P < 0.01). CONCLUSIONS: Haemodiafiltration with online regeneration of ultrafiltrate and online HDF are highly biocompatible techniques and no significant difference between HFR and online HDF was observed in terms of reduction of inflammatory markers. Further studies with a longer follow-up are needed to evaluate the clinical relevance of the online endogenous reinfusion to counteract the chronic inflammatory state of the uraemic patient.

[Effects of reduced dialysate calcium on mineral metabolism in hemodialysis patients].

AIM: To study the effects of decreased dialysis calcium on mineral metabolism. METHODS: Dialysis calcium concentration was switched from 3.0 mEq/L to 2.5 mEq/L. Changes of serum Ca, P, and PTH were monitored for 6 months in 58 hemodialysis patients. RESULTS: Serum calcium decreased 2 weeks after the switch of dialysate, although it returned to the basal level after 6 months because of increased dosage of vitamin D. Phosphorus transiently increased after the switch. I-PTH increased in patients whose i-PTH before the switch was less than 100 pg/mL. PTH decreased in patients whose i-PTH exceeded 300 pg/mL. CONCLUSION: Decreased dialysis calcium produced lower serum calcium and better PTH control.

The influence of dialysate calcium on the therapeutic effects of sevelamer hydrochloride in hemodialysis patients with secondary hyperparathyroidism under treatment of intravenous vitamin d metabolites.

The management of hyperphosphatemia is essential to treat secondary hyperparathyroidism and to prevent ectopic calcification. Sevelamer hydrochloride (sevelamer), a new phosphate binder that contains neither aluminum nor calcium, which could be theoretically beneficial for the management of hyperphosphatemia in dialysis patients with secondary hyperparathyroidism who are receiving intravenous vitamin D metabolites (maxacalcitol or calcitriol). To reduce calcium loads, a dialysate calcium concentration of 2.5 mEq/L is recommended by Kidney Disease Outcome Quality Initiative (K/DOQI) guidelines. In Japan, a dialysate calcium concentration of 3.0 mEq/L prevails. We investigated the influence of dialysate calcium on the therapeutic effect of sevelamer in 40 hemodialysis patients who are under treatment of intravenous vitamin D metabolites for secondary hyperparathyroidism (VD(+)) and compared the results with those of 41 patients who had not received vitamin D metabolites (VD(-)). Serum phosphorus and calcium-phosphorus products showed no significant change by sevelamer in either the VD(+) subgroup of patients receiving hemodialysis with dialysate calcium of 2.5 mEq/L (DCa2.5) or those receiving hemodialysis with dialysate calcium of 3.0 mEq/L (DCa3.0), while serum phosphorus and calcium-phosphorus products decreased in both the VD(-) subgroups. Serum calcium decreased in the DCa2.5 subgroup and did not change in the DCa3.0 subgroup in both the VD(+) and the VD(-) subjects. Parathyroid hormone and alkaline phosphatase increased in the DCa2.5 subgroup and did not change in the Ca 3.0 subgroup in the VD(+) subjects. Serum calcium decreased in both subgroups in the VD(-) subjects. Parathyroid hormone obtained after sevelamer administration in the VD(-) group was within the target range of the K/DOQI guidelines. In conclusion, the concomitant use of sevelamer as a phosphate binder and the dialysate of calcium concentration of 2.5 mEq/L have possibilities for worsening secondary hyperparathyroidism in patients receiving intravenous vitamin D.

Is 2.5 mEq/L the optimal calcium concentration of dialysate in the use of sevelamer hydrochloride? A study of the dialysate calcium concentration recommended by K/DOQI guidelines.

We tested the effect of three different dialysate calcium concentrations on calcium-phosphorus metabolism during the use of sevelamer hydrochloride. After a calcium-containing phosphate binder was switched to sevelamer, the serum calcium, phosphorus, and intact parathyroid hormone levels and the markers of bone turnover were measured in the patients whose dialysate calcium concentrations were 2.5, 2.75, and 3.0 mEq/L. As a result, in the 2.75-mEq/L group, the serum calcium concentrations decreased and the intact parathyroid hormone level increased significantly. In the 2.5-mEq/L group, transient hypocalcemia occurred and the levels of both bone-alkaline phosphatase and osteocalcin increased. In the 3.0-mEq/L group, the serum calcium concentrations did not change significantly and only bone-alkaline phosphatase increased. If a calcium-containing phosphate binder is completely switched to sevelamer, dialysis using a dialysate calcium concentration below 3.0 mEq/L may result in hypocalcemia and acceleration of bone turnover.