Effective glutamate clearance from the systemic circulation by hemodialysis: Potential relevance for cerebral ischemia management.

High glutamate levels after head trauma or cerebral ischemia have neurotoxic effects. The objective of the present study was to evaluate the efficacy of hemodialysis to remove glutamate from the blood and to assess the behavior of this small molecule. Ten patients with end-renal disease on hemodialysis were included in the study. Glutamate clearance was evaluated within the first hour of hemodialysis on a midweek dialysis day on five patients who underwent low flux hemodialysis, whereas the other five patients underwent highly efficient hemodialysis (high flux hemodialysis on one day and online hemodiafiltration on another day). Glutamate clearance with hemodialysis was very effective and did not show any differences between the techniques (low flux: 214 [55], high flux: 204 [37], online hemodiafiltration: 202 [16], median (interquartile range), P = .7). Glutamate clearance was almost equivalent to vascular access plasma flow and it was not affected by dialyzer permeability or ultrafiltration rate. After a hemodialysis session, a significant decrease in glutamate blood level was observed (prehemodialysis: 59.7 [36.1], posthemodialysis 37.0 [49.2], P = .005). Dialysis performed under fasting condition showed higher glutamate reduction rate (60%) than that under feeding condition (20%). Hemodialysis may be an effective method to reduce glutamate blood levels, and the molecule clearance does not differ between the different techniques used. Considering previous results in experimental models, hemodialysis without hemodynamic stress, could be considered for reducing glutamate neurotoxic effects in acute ischemic strokes of patients in chronic hemodialysis programs.

Hypomagnesaemia in haemodialysis is associated with increased mortality risk: its relationship with dialysis fluid. / La hipomagnesemia en hemodiálisis se asocia a mayor riesgo de mortalidad: su relación con el líquido de diálisis.

Hypomagnesaemia in haemodialysis (HD) is associated with increased mortality risk: its relationship with dialysis fluid (DF). INTRODUCTION: Low concentrations of magnesium (Mg) in blood have been linked to the development of diabetes, hypertension, arrhythmias, vascular calcifications and an increased risk of death in the general population and in haemodialysis patients. The composition of the dialysis fluid in terms of its magnesium concentration is one of the main determinants of magnesium in haemodialysis patients. OBJECTIVE: To study magnesium concentrations in haemodialysis patients, their predictive mortality rate and what factors are associated with hypomagnesaemia and mortality in haemodialysis. METHODS: Retrospective study of a cohort of prevalent haemodialysis patients followed up for two years. Serum magnesium was measured every six months. The analysis used the initial and average magnesium values for each patient, comparing patients with magnesium below the mean (2.1mg/dl) with those with magnesium above the mean. During the follow-up, three types of dialysis fluid were used: type 1, magnesium 0.5 mmol/l; type 3, magnesium 0.37 mmol/l (both with acetate); and type 2, magnesium 0.5 mmol/l with citrate. RESULTS: We included 137 haemodialysis patients in the study, of which 72 were male and 65 were female, with a mean age of 67 (15) [26-95] years old. Of this group, 57 patients were diabetic, 70 were on online haemodiafiltration (OL-HDF) and 67 were on high-flow haemodialysis (HF-HD). The mean magnesium of the 93 patients with dialysis fluid type 1 was 2.18 (0.37) mg/dl. In the 27 patients with dialysis fluid type 3 it was 2.02 (0.42) mg/dl. And in the 17 with dialysis fluid type 2 it was 1.84 (0.24) mg/dl (p=.01). There was a pronounced direct relationship between Mg and P and albumin. After a mean follow-up of 16.6 (8.9) [3-24] months, 77 remained active, 24 had died and 36 had been transplanted or transferred. Patients with magnesium above than 2.1mg/dl had a longer survival (p=.008). The survival of patients with the three types of dialysis fluid did not differ significantly (Log-Rank, p=.424). Corrected for blood magnesium, patients with dialysis fluid with citrate have better survival (p=.009). The COX regression analysis shows how age, serum albumin, magnesium, dialysis technique and type of dialysis fluid have an independent predictive mortality rate. CONCLUSIONS: Low serum magnesium levels have a greater association with an increased risk of mortality compared to high levels. The type of dialysis fluid affects the magnesium concentration and the risk of death.

[High prevalence of asymptomatic COVID-19 in haemodialysis: learning day by day in the first month of the COVID-19 pandemic]. / Alta prevalencia de COVID-19 asintomático en hemodiálisis. Aprendiendo día a día el primer mes de pandemia de COVID-19.

Dialysis patients are a risk group for SARS-CoV-2 infection and possibly further complications, but we have little information. The aim of this paper is to describe the experience of the first month of the SARS-CoV-2 pandemic in a hospital haemodialysis (HD) unit serving the district of Madrid with the second highest incidence of COVID-19 (almost 1,000 patients in 100,000h). In the form of a diary, we present the actions undertaken, the incidence of COVID-19 in patients and health staff, some clinical characteristics and the results of screening all the patients in the unit. We started with 90 patients on HD: 37 (41.1%) had COVID-19, of whom 17 (45.9%) were diagnosed through symptoms detected in triage or during the session, and 15 (40.5%) through subsequent screening of those who, until that time, had not undergone SARS-CoV-2 PCR testing. Fever was the most frequent symptom, 50% had lymphopenia and 18.4% <95% O2 saturation. Sixteen (43.2%) patients required hospital admission and 6 (16.2%) died. We found a cluster of infection per shift and also among those using public transport. In terms of staff, of the 44 people involved, 15 (34%) had compatible symptoms, 4 (9%) were confirmed as SARS-CoV-2 PCR cases by occupational health, 9 (20%) required some period of sick leave, temporary disability to work (ILT), and 5 were considered likely cases. CONCLUSIONS: We detected a high prevalence of COVID-19 with a high percentage detected by screening; hence the need for proactive diagnosis to stop the pandemic. Most cases are managed as outpatients, however severe symptoms are also appearing and mortality to date is 16.2%. In terms of staff, 20% have required sick leave in relation to COVID-19.

Unlike Kt, high Kt/V is associated with greater mortality: The importance of low V. / El Kt/V alto, a diferencia del Kt, se asocia a mayor mortalidad: importancia de la V baja.

INTRODUCTION: Kt/V has been used as a synonym for haemodialysis dose. Patient survival improved with a Kt/V>1; this target was subsequently increased to 1.2 and 1.3. The HEMO study revealed no significant relationship between Kt/V and mortality. The relationship between Kt/V and mortality often shows a J-shaped curve. Is V the confounding factor in this relationship? The objective of this study is to determine the relationship between mortality and Kt/V, Kt and body water content (V) and lean mass (bioimpedance). METHODS: We studied a cohort of 127 prevalent haemodialysis patients, who we followed-up for an average of 36 months. Kt was determined by ionic dialysance, and V and nutrition parameters by bioimpedance. Kt/V, Kt corrected for body surface area (Kt/BSA) and target Kt/BSA were calculated. The mean data from 18,998 sessions were used as haemodialysis parameters, with a mean of 155 sessions per patient. RESULTS: Mean age was 70.4±15.3 years and 61% were male; 76 were dialysed via an arteriovenous fistula and 65 were on online haemodiafiltration. Weight was 70.6 (16.8)kg; BSA 1.8 (0.25) m2; total body water (V) 32.2 (7.41) l and lean mass index (LMI) 11.1 (2.7)kg/m2. Mean Kt/V was 1.84 (0.44); Kt 56.1 (7)l and Kt/BSA 52.8 (10.4)l. The mean target Kt/BSA was 49.7 (4.5)l. Mean Kt/BSA-target Kt/BSA +6.4 (7.0)l. Patients with a higher Kt/V had worse survival rates than others; with Kt this is not the case. Higher Kt/V values are due to a lower V, with poorer nutrition parameters. LMI and serum albumin were the parameters that best independently predicted the risk of death and are lower in patients with a higher Kt/V and lower V. CONCLUSION: Kt/V is not useful for determining dialysis doses in patients with low or reduced body water. Kt or the Kt/BSA are proposed as an alternative.

Higher Proportion of Non-1-84 PTH Fragments in Peritoneal Dialysis Patients Compared to Hemodialysis Patients Using Solutions Containing 1.75 mmol/l Calcium.

Background: The prevalence of low- turnover bone disease (LTBD) in peritoneal dialysis (PD) patients is higher than in hemodialysis (HD) patients. LTBD patients may be at risk for vascular calcification, and cardiovascular disease. Current therapy for chronic kidney disease metabolic bone disorders (CKD-MBD) is guided by biochemical parameters, as bone biopsy is not used in routine clinical care. Methods: We assessed intact PTH (iPTH: 1-84PTH plus non-1-84PTH), 1-84PTH, and the 1-84PTH/non-1-84PTH ratio in 129 hemodialysis and 73 PD prevalent patients dialyzed with solutions containing 1.75 mmol/L calcium. Results: Hemodialysis and PD patients presented similar iPTH and tCa values and prevalence of putative LTBD as defined according to KDOQI iPTH cut-off levels or 1-84 PTH levels. However, iCa accounted for a higher percentage of tCa in PD (53%) than in hemodialysis (39%) p < 0.001, and the 1-84PTH/non-1-84PTH ratio was lower in PD than in hemodialysis patients (0.44 ± 0.12) vs. (0.60 ± 0.10), p < 0.001. The prevalence of putative LTBD when using the coexistence of 1-84PTH/non-1-84PTH ratio < 1.0 and iPTH < 420 pg/m, was higher in PD than in hemodialysis patients (73 vs. 16% respectively, p < 0.001). In a multivariate logistic regression analysis, dialysis modality was the main determinant of the 1-84PTH/non-1-84PTH ratio. Conclusion: Solutions containing 1.75 mmol/L calciums are associated to a higher proportion of non-1-84PTH fragments in PD than in HD patients. Different analytical criteria result in widely different estimates of LTBD prevalence, thus impairing the ability of clinicians to optimize therapy for CKD-MBD.

Citrate dialysate does not induce oxidative stress or inflammation in vitro as compared to acetate dialysate. / El líquido de diálisis con citrato no induce in vitro estrés oxidativo ni inflamación en comparación con el acetato.

Increased acetataemia during haemodialysis sessions has been associated with a number of abnormalities, including increased oxidative stress, pro-inflammatory cytokines and nitric oxide synthesis. However, citric acid may play an alternative role to acetate as a dialysate stabiliser given that the effect of citrate on complement and leukocyte activation is different to that of acetate. The purpose of this study was to compare the inflammatory effect in immunocompetent blood cells of acetate dialysate and citrate dialysate. MATERIAL AND METHODS: The effect of acetate and/or citrate was investigated in the whole blood of uraemic patients and in healthy in vitro samples. Four types of dialysate were tested: dialysate 1, acetate-free with 1mmol/L of citrate; dialysate 2, with 0.8mmol/L of citrate and 0.3mmol/L of acetate; dialysate 3, citrate-free with 3mmol/L of acetate; and dialysate 4, citrate-free with 4mmol/L of acetate. The cell types used were: human monocyte culture (THP-1); and peripheral blood mononuclear cells (PBMCs) from healthy subjects and uraemic patients on haemodialysis. ICAM-1 was determined and levels of reactive oxygen species and total microvesicles were quantified. RESULTS: Unlike the citrate dialysates, the dialysates with acetate (dialysate 3 and dialysate 4) induced increased ICAM-1 expression density in THP-1 cells; an increase in ICAM-1 expression was observed in the immunocompetent cells of healthy subjects with acetate dialysate (dialysate 3 and dialysate 4) but not with citrate dialysate (dialysate 1 and dialysate 2). No significant ICAM-1 differences were found between the different dialysates in the cells of haemodialysed patients. Reactive oxygen species expression and the number of microvesicles increased significantly with acetate dialysate but not with citrate dialysate in the cells of both healthy subjects and haemodialysed patients. CONCLUSIONS: At the concentrations in which it is generally used in clinical practice, acetate-based dialysate increases oxidative stress and the total number of microvesicles and may induce other pro-inflammatory stimuli typical of uraemic patients on haemodialysis. Citrate dialysates do not induce this activation, which could make them a suitable alternative in clinical practice.

Residual Renal Function in Hemodialysis and Inflammation.

Residual renal function (RRF) has an important effect on uremic toxin clearance, on volume control, on quality of life, and on mortality. In patients with chronic kidney disease (CKD), microinflammation with an increased percentage of CD14+ /CD16++ inflammatory monocytes has been reported, even with no clinical evidence of inflammation. No correlation has been established between these and RRF in hemodialysis (HD) patients. Our objective was to assess the relationship between RRF and the inflammatory parameters in HD patients. Cross-sectional observational study was carried out on 69 adult patients on chronic HD for at least 6 months, from which demographic, analytic and HD-technique data were collected and the following were measured: (i) RRF with average urea and creatinine clearance ((CCr + CU)/2) in 24-h urine (if >1 mL/min and diuresis >100 mL/day, RRF was considered); (ii) Inflammation through biochemical parameters (C-reactive protein, ß2 microglobulin, albumin) and monocyte subpopulations in peripheral blood. The average age was 70.9 [40-88] years old; 38 (55.1%) were male; and 25 (36.2%) were diabetic. 43.5% (30/69) presented RRF, with an average of ((CCr + CU)/2): 1.8 (2.6) mL/min and diuresis: 454.5 (569) mL /24 h. Patients with RRF presented lower concentrations of C-reactive protein (6.2 vs 21.4 mg/L) (P = 0.038) and a lower percentage of non-classical CD14+ /CD16++ monocytes (14.6 vs. 28.3%, P = 0.02). In our study, patients with RRF present lower concentrations of inflammatory parameters, which is another reason why its preservation is an essential objective in HD.

Universal Sustained Viral Response to the Combination of Ombitasvir/Paritaprevir/Ritonavir and Dasabuvir with/without Ribavirin in Patients on Hemodialysis Infected with Hepatitis C Virus Genotypes 1 and 4.

BACKGROUND: Hepatitis C virus (HCV) infection is highly prevalent among patients on hemodialysis (HD) and is associated with poor prognosis. Treatment with interferon and ribavirin is poorly tolerated, and few data are available on the impact of new direct-acting antivirals (DAAs). This study was intended to analyze the efficacy and safety of treatment with a combination of ombitasvir/paritaprevir/ritonavir and dasabuvir with/without ribavirin in HCV-infected patients on HD from 3 hospitals. METHODS: This is a multicentric study. We analyze the clinical course of all patients on HD with HCV infection who had been treated with the combination of ombitasvir/paritaprevir/ritonavir and dasabuvir in 3 hospitals in Madrid, Spain. All patients under treatment had undergone Transient elastography (FibroScan®) and HCV RNA (PCR) and HCV genotype were determined simultaneously. RESULTS: Thirty-five patients aged 53.3 ± 8.9 years (68.6% males) and with genotypes 1 and 4 were treated with the DAA regimen, and 17 were also given ribavirin. The most common etiology was glomerular disease. Sustained viral response was achieved in 100% of patients. Adverse effects were negligible, and no patient had to discontinue treatment. The most significant side effect was anemia, which led to a significant increase in the dose of erythropoiesis-stimulating agents. Anemia was more marked in patients receiving ribavirin. No patients required transfusions. CONCLUSION: A combination of ombitasvir/paritaprevir/ritonavir and dasabuvir with/without ribavirin for the treatment of HCV in patients on HD is highly effective and causes minimal side effects. This regimen represents a major advance in disease management. A considerable improvement in prognosis seems likely.

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.

Is it useful to increase dialysate flow rate to improve the delivered Kt?

BACKGROUND: Increasing dialysate flow rates (Qd) from 500 to 800 ml/min has been recommended to increase dialysis efficiency. A few publications show that increasing Qd no longer led to an increase in mass transfer area coefficient (KoA) or Kt/V measurement. Our objectives were: 1) Studying the effect in Kt of using a Qd of 400, 500, 700 ml/min and autoflow (AF) with different modern dialysers. 2) Comparing the effect on Kt of water consumption vs. dialysis time to obtain an individual objective of Kt (Ktobj) adjusted to body surface. METHODS: This is a prospective single-centre study with crossover design. Thirty-one patients were studied and six sessions with each Qd were performed. HD parameters were acquired directly from the monitor display: effective blood flow rate (Qbe), Qd, effective dialysis time (Te) and measured by conductivity monitoring, final Kt. RESULTS: We studied a total of 637 sessions: 178 with 500 ml/min, 173 with 700 ml/min, 160 with AF and 126 with 400 ml/min. Kt rose a 4% comparing 400 with 500 ml/min, and 3% comparing 500 with 700 ml/min. Ktobj was reached in 82.4, 88.2, 88.2 and 94.1% of patients with 400, AF, 500 and 700 ml/min, respectively. We did not find statistical differences between dialysers. The difference between programmed time and Te was 8' when Qd was 400 and 500 ml/min and 8.8' with Qd = 700 ml/min. Calculating an average time loss of eight minutes/session, we can say that a patient loses 24' weekly, 312' monthly and 62.4 hours yearly. Identical Kt could be obtained with Qd of 400 and 500 ml/min, increasing dialysis time 9.1' and saving 20% of dialysate. CONCLUSIONS: Our data suggest that increasing Qd over 400 ml/min for these dialysers offers a limited benefit. Increasing time is a better alternative with demonstrated benefits to the patient and also less water consumption.

Evaluation of a polynephron dialysis membrane considering new aspects of biocompatibility.

PURPOSE: The biocompatibility of dialyzers may influence the inflammatory state of hemodialysis patients. This study compares the effect of a high-flux polynephron membrane with other high-flux membranes, helixone and polyamide, on some inflammation biomarkers based on the analysis of circulating mononuclear cells (MC). METHODS: The study included 47 patients on hemodialysis with helixone and polyamide; 9 formed the control group, without changes in their dialyzers throughout the study, and 38 formed the intervention group, in which their dialyzers were replaced by polynephron. In both groups, blood samples were taken at the beginning of the study before and after hemodialysis session, and at the end of the study 4 months later. In each extraction, biochemical parameters were determined, and MC isolated using Ficoll gradient. Production of reactive oxygen species and the percentage of activated MC (CD14+CD16+) were measured by flow cytometry, and protein levels of heat-shock proteins (Hsp70/Hsp90) studied by Western blot. RESULTS: After 1 hemodialysis session with different membranes, no significant differences were observed in the different parameters considered. After 4 months of dialysis with polynephron, a significant reduction in the percentage of CD14+CD16+ and in the ß2-microglobulin reduction ratio were found, with respect to helixone and polyamide, without changes in the other parameters analyzed. CONCLUSIONS: The use of polynephron for 4 months reduces the percentage of CD14+CD16+ compared to helixone and polyamide, suggesting a better profile regarding activation of the inflammatory response. These findings could be explained by a better biocompatibility or an increased reduction of medium-sized toxic molecules.

Psychosocial factors and adherence to drug treatment in patients on chronic haemodialysis.

BACKGROUND: The daily pill burden in hemodialysis patients is one of the highest reported to date in any chronic disease. The adherence to prescribed treatment has implications on the quality of life, the survival of patients, and the economic cost of their treatment, this being a priority public health issue. OBJECTIVE: To evaluate the adherence to pharmacological treatment examining, among the possible causes of non-adherence, psychosocial factors such as depression, anxiety, cognitive impairment and social support. METHOD: Transversal-observational study of thirty five patients that suffer from chronic renal disease and who are on manteinance hemodialysis, evaluated by self-reported measures. RESULTS: Non-adherent patients have significant higher depression index than adherent patients. Anxiety, cognitive impairment and social support do not show a significant relation with the degree of adherence or compliance with farmacological treatment. CONCLUSIONS: These results suggest that psychological intervention in chronic haemodialysis patients with a severe depression index could increase the degree of fulfillment and general well-being of renal patients.

A lower proportion of circulating active parathyroid hormone in peritoneal dialysis does not allow the pth inter-method adjustment proposed for haemodialysis.

INTRODUCTION: Parathyroid hormone (PTH) shows a strong correlation with histomorphometric and biochemical parameters of bone turnover, however its measurement presents limitations due to inter-method variability. Circulating PTH is a mixture of peptides, but only on its whole form (1-84 PTH) is responsible of PTH biological activity. Carboxyl-terminal fragments exhibit antagonist actions and their proportion differs at each stage of chronic kidney disease, as consequence of differences on their renal clearance. The aim of this study is to evaluate possible differences in the proportion of these fragments according to dialysis type: haemodialysis (HD) or peritoneal dialysis (PD). MATERIAL AND METHODS: Serum total (Ca) and ionized calcium (iCa), phosphate (P), carboxyl-terminal telopeptides of collagen type I (BCTx) were measured in 73 patients on PD (46 men and 27 women with an age between 22 and 82 years). PTH was quantified by six second generation assays (one isotopic and five chemiluminescence assays) and by one third generation PTH method. RESULTS: Mean serum levels of Ca, iCa, P and BCTx were 9.03, 4.76, 4.73 mg/dl and 1181 pmol/l, respectively. Significant differences were observed in PTH values according to the method used. Adjustment of PTH results to PTH Allegro (Nichols) range of 150-300 nmol/l in PD patients showed higher values than those assessed previously for HD population. The percentage of biologically active 1-84 PTH as the 1-84 PTH/ 7-84 PTH ratio in PD were significantly lower than in HD patients, reflecting the higher proportion of 7-84 PTH circulating fragments for a given intact PTH result in PD. CONCLUSIONS: PD patients have a higher proportion of 7-84 PTH circulating fragments. Consequently, the inter-method adjustment algorithms proposed for HD patients are not useful for PD patients. This study proposes alternative algorithms for PTH inter-method adjustment to be applied in PD.

A comparison of the effectiveness of two online haemodiafiltration modalities: mixed versus post-dilution.

INTRODUCTION: Haemodiafiltration (HDF) with high reinfusion volumes is the most effective technique for clearing uraemic toxins. There are various modalities depending on the location where the replacement volume is administered in the extracorporeal circuit: pre-dilution, mixed or mid-dilution and post-dilution, in which the infusion is carried out pre-dilution, pre- and post-dilution simultaneously and post-dilution, respectively. OBJECTIVE: Compare the clearance of small, medium-sized and protein-bound molecules and the convective volume administered in online HDF (OL-HDF) in post-dilution and mixed (pre-post-dilution) infusion. MATERIAL AND METHOD: A prospective, randomised, crossover study comparing post-dilution and mixed OL-HDF. Patients (n=8) were randomly assigned to receive 6 sessions in each technique. We conducted 89 sessions, of which 68 were at a scheduled time (ST) and 21 at an effective time (ET). We determined the reduction rate (RR) percentages for various substances and the infusion volumes. The RR study was performed using ET. RESULTS: The KT value obtained was greater with post-dilution OL-HDF [68 (8.1) compared to 64.9 (8.8) litres] (P=.009) when patients were dialysed at ST. This difference disappeared when dialysis was performed at ET. The difference between ST and ET was greater in mixed HDF than in post-dilution HDF [10.3 (7.4) compared to 6.5 (3.1) minutes, P=.02]. We found no differences in the RR of the substances analysed. CONCLUSION: Mixed OL-HDF is not inferior to post-dilution OL-HDF either in the clearance of small and medium-sized molecules or in the clearance of protein-bound molecules at the same ET.

On-line haemodiafiltration improves response to calcifediol treatment.

INTRODUCTION: 25-hydroxy vitamin D (25-OH-vit D) levels in the blood are associated with multiple pathologies. "Normal" values have been defined based on cardiovascular risk, and under this framework, patients with chronic kidney disease often have a deficit. 25-OH-vit D replacement in patients on haemodialysis (HD), in which dosage has not yet been clearly established, is becoming a constant in our daily practice. OBJECTIVE: To assess whether dialysis technique influences the baseline concentration of 25-OH-vitamin D and the response to supplements. METHOD: Prospective observational study of two cohorts of patients, those patients treated with calcifediol and those untreated (controls). Blood levels of Ca, P, PTH, and 25-OH-vit D were measured in 59 prevalent patients on HD (35 male; mean age: 65.2 (15.7) years) in November 2010. Thirty-six patients with 25-OH-vit D<10 ng/ml were treated with weekly calcifediol (Hidroferol®, 1 ampoule: 266 µg) since January 2011, which was administered after HD by a nurse. They received 6 doses, and blood levels were measured again in March 2011. We compared the response based on the technique of HD (online haemodiafiltration [OL-HDF] vs HD). RESULTS: Mean baseline values (n=59): 25-OH-vit D: 9.8 (7.0)ng/ml, Ca: 9.3 (0.5)mg/dl, P: 4.5 (1.4)mg/dl, and iPTH: 299 (224)pg/ml. There were no differences by age, sex, or dialysis technique (HD vs OL-HDF). Treated patients (n=36): 25-OH-vit D levels rose from 6.2 (3.4)ng/ml to 51 (22.9)ng/ml (P<.0001), without significant changes in Ca. Serum phosphate increased an average of 0.6 (1.4)mg/dl, from 4.4 mg/dl to 5mg/dl, (P=.015). PTH decreased an average of 85 (208)pg/ml (P=.023). In these patients, the indication for phosphate binders increased by an average dose equivalent of 0.47 (0.82)mg/dl (P<.001). The 13 patients under treatment with OL-HDF reached 25-OH-vit D levels significantly higher than the 23 treated on HD: 63 (21)ng/ml vs 43 (21)ng/ml (P=.011). Dual treatment with native and active Vit D was associated with significantly increased levels of P (P=.043). Untreated patients (n=23): 25-OH-vit D levels decreased from 15.3 (7.5)ng/ml in November to 11.1 (6.8)ng/ml in March (P<.01), without significant changes in P or PTH and without differences according to age. 25-OH-vit D levels declined in patients on HD (15) but not in patients on OL-HDF. CONCLUSION: The patients on haemodialysis have low or very low baseline values for 25-OH-vit D. The response to treatment with calcifediol is good, with the most marked improvement occurring in patients on OL-HDF. Furthermore, 25-OH-vit D levels decreased in untreated patients, which was probably correlated with the lower sun exposure in winter. Some patients experienced an increase in phosphataemia despite increasing the dosage of phosphate binders, mainly in those receiving treatment with active vitamin D.