Effect of type of dialysis membrane on bone in haemodialysis patients.

BACKGROUND: Uraemic bone disease is the result of a number of factors modulating bone formation and resorption in a complex manner. In the present study, the hypothesis tested was that the type of haemodialysis membrane used for renal replacement therapy might also play a role. METHODS: We conducted a prospective, open study in 24 chronic haemodialysis patients who were randomized to dialysis treatment with either cellulosic (CELL group, n=11) or polyacrylonitrile (AN-69 group, n=13) membrane for 9 months. Repeated determinations of plasma parameters reflecting bone turnover were done in all patients, and a bone biopsy in a subgroup at the start and end of study. RESULTS: At the start, mean plasma intact parathyroid hormone levels were comparable between the two groups and they did not vary significantly at 9 months of treatment. Similarly, plasma bone-specific alkaline phosphatase and osteocalcin (markers of bone formation), and cross-laps (marker of bone resorption) remained unchanged. However, plasma insulin-like growth factor-I (IGF-I) progressively decreased from 169 to 119 ng/ml in AN-69 group (P<0.01), whereas it remained unchanged in CELL group. In addition, the levels of IGF binding protein (IGFBP)-1 and IGFBP-2 were increased while the levels of IGFBP-5 were decreased in AN-69 group. In the five patients of each group who had repeat bone biopsies, histomorphometric analysis showed a decrease in osteoblast surface, osteoclast surface and osteoclast number in AN-69 group at 9 months, compared with baseline values measured at the start of the study. In contrast, all three parameters significantly increased in the CELL group at 9 months (P<0.001 for the difference between each of the three parameters).Bone formation rate decreased by 31% in the AN-69 group, but increased by 50% in CELL group. However, this latter difference was not statistically significant. Plasma interleukin (IL)-6 and soluble IL-6 receptor levels did not change in the two groups of patients who had undergone bone biopsy. CONCLUSION: Dialysis with CELL membrane was associated with increased bone turnover whereas the use of AN-69 membrane was associated with decreased bone turnover, suggesting a beneficial effect of the latter on high-turnover uraemic bone disease. However, as the number of patients with repeat bone biopsies was small, these findings need to be confirmed in a larger study. Further studies are also needed to evaluate whether or not the changes in IGF system components play a role in decreased bone cell activity in patients on dialysis using the AN-69 polyacrylonitrile membrane.     

Effect of dialysis flux and membrane material on dyslipidaemia and inflammation in haemodialysis patients.

BACKGROUND: Dyslipidaemia, inflammation and oxidative stress are prominent risk factors that potentially cause vascular disease in haemodialysis patients. Dialysis modalities affect uraemic dyslipidaemia, possibly by modifying oxidative stress, but the effects of dialyser flux and membrane material on atherogenic remnant particles and oxidized low-density lipoproteins (LDL) are unknown. METHODS: We performed a randomized crossover study in 36 patients on haemodialysis to analyse the effect of dialyser flux and membrane material on plasma lipids, apolipoproteins and markers of inflammation and oxidative stress. Stable patients on low-flux dialysis with polysulphone for >/=6 weeks were assigned to high-flux polysulphone or high-flux modified cellulose with similar dialyser surface area and permeability characteristics and crossed over twice every 6 weeks. RESULTS: Thirty patients completed the study per protocol. Treatments with high-flux polysulphone and modified cellulose lowered serum triglyceride (by 20% and 10%, respectively; P<0.05) and remnant-like particle cholesterol by 32% (P<0.001) and 11% (NS) after the first 6 weeks of treatment. Oxidized LDL decreased significantly with high-flux polysulphone, but not with modified cellulose. Apolipoproteins CII and CIII were reduced, whereas the ratio CII/CIII was increased (all P<0.05). Acute-phase proteins and LDL and high-density lipoprotein cholesterol remained unaffected. CONCLUSIONS: This randomized crossover study demonstrates a potent effect of high-flux haemodialysis on uraemic dyslipidaemia. Polysulphone membrane material showed superiority on oxidatively modified LDL, an indicator of oxidative stress in haemodialysis patients.     

Blood oxidative stress and lipoprotein oxidizability in haemodialysis patients: effect of the use of a vitamin E-coated dialysis membrane.

BACKGROUND: Oxidative stress has been shown in haemodialysis patients in relation with an increased production of free radicals due to membrane-induced complement and leukocyte activation. In order to minimize membrane bioincompatibility and thereby oxidative stress, more compatible filters have been perfected. Among them, a high-flux vitamin E-coated membrane (CL-EE) has been proposed recently. In vivo, little data is available on the consequences of the use of vitamin E-coated membranes. In the present study, the effects of a 3-month use of CL-EE dialysis membranes compared to conventional membranes have been evaluated in 12 haemodialysis patients on the blood oxidative stress status before and after the dialysis session. METHODS: We determined the lipid peroxidation status (plasma thiobarbituric acid-reactive substances) and antioxidant defence (erythrocyte Cu,Zn-superoxide dismutase and plasma and erythrocyte glutathione peroxidase activities, plasma vitamin E, beta-carotene, vitamin A and total antioxidant status). Also, we simultaneously determined the antioxidant content and the copper oxidizability of isolated low density- and high density-lipoproteins (LDLs and HDLs). RESULTS: The main consequence observed under these conditions was a marked enrichment of plasma with vitamin E, which was also significantly and selectively noted in HDLs (no changes in LDL vitamin E content), perhaps related to a specific storage capacity for vitamin E in HDLs of haemodialysis patients. The beta-carotene content of plasma, LDLs and HDLs was also higher after use of vitamin E-coated membranes than after use of high-flux biocompatible membranes. HDL copper oxidizability was reduced (as shown by an increased lag time) before dialysis after use of CL-EE membranes compared to conventional membranes, whereas LDL oxidizability remained unchanged. CONCLUSION: A 3-month use of vitamin E-coated membranes resulted in a significant increase in plasma and HDL vitamin E content, associated with a lower oxidizability of HDLs, which could be beneficial for haemodialysis patients.     

Insomnia in maintenance haemodialysis patients.

BACKGROUND: Studies in the last 15 years have shown a high prevalence of sleep disorders in maintenance haemodialysis (HD) patients. METHODS: To investigate whether the new technical and therapeutic advances of the last decade have had a positive impact on sleep disturbances in HD patients: 694 patients (384 males, 310 females) were surveyed using a specific questionnaire; their clinical, lifestyle and dialysis data were also recorded. RESULTS: Forty-five per cent of patients (n=311; 156 males, 155 females) complained of insomnia, defined either by delayed sleep onset and/or night-time waking, and were included in the insomnia group; the remainder were used as controls (control group). There was a significantly higher risk of insomnia in patients with >12 months on dialysis, in patients dialysed in the morning (P<0.003), and in patients with higher parathyroid hormone (PTH) levels (P<0.05). Body mass index, body weight gain and blood pressure did not differ between the groups, and neither did the dialysis parameters. Creatinine and urea plasma levels were higher in the control group vs the insomnia group (P<0.001), but there was no difference in haemoglobin concentrations or use of erythropoietin, calcitriol and antihypertensive drugs. Cigarette smoking, caffeine or alcohol intake were comparable in the two groups. The most frequently recorded sleep disorders were night-time waking (92%), trouble falling asleep (67%) and early morning waking (62%). Restless leg symptoms were described in 52% of patients with insomnia. CONCLUSIONS: The prevalence of insomnia in HD patients is still very high; elderly patients, and those with longer time on dialysis and high levels of PTH are at major risk of insomnia, whereas type of dialysis, haemoglobin levels and behavioural factors do not seem to play a critical role in determining this sleep disorder.     

Choice of dialysis membrane does not influence the outcome of residual renal function in haemodialysis patients

It has been recently proposed that haemodialysis membrane choicemay influence the maintenance of residual renal function. Theaim of the present study was to prospectively analyse the effectof membrane choice on the outcome of renal function in patientsentering a chronic haemodialysis programme. Twenty-two patientsfrom four hospitals have been randomly assigned to be dialysedwith either polysulphone(PSF)/polyacrylonitrile (PAN) (groupA; n=9), or cuprophane membranes (group B; n=13). Basal andmonthly serum biochemistry, residual creatinine clearance (C_cr)and urine volume (Vu), pharmacological and dialytic treatment,diet, and haemodialysis-related complications were recorded.A significant decrease was observed in the two most relevantvariables, i.e. remnant C_cr and Vu, within 3 months of startinghaemodialysis, with stabilization during the further follow-up.Such decrease was similar (P NS) for both groups A and B throughoutthe 9-month observation period. In conclusion, our results suggest that the choice of haemodialysismembrane does not influence the outcome of the residual renalfunction. Renal function decreased significantly within 3 monthson haemodialysis, independently of the type of dialyser membrane.     

Phosphate removal in haemodialysis: Effect of two different dialysis membranes

Summary: Phosphate removal with two different dialysis membranes (a standard cellulose acetate membrane and a high performance cellulose diacetate membrane) were studied in ten haemodialysis patients. All patients were dialysed sequentially with two membranes (surface area was 1.5 m²) against bicarbonate buffered dialysis for 4 hours three times a week. With the diacetate membrane, the instantaneous clearances of urea and phosphate after 1 hour of haemodialysis were significantly higher than with the cellulose membrane. Also, the weekly total amount of urea and phosphate removal were significantly increased with the diacetate membrane (a 15% increase in urea and a 16% increase of phosphate). Although there was a significant increase in urea reduction ratio and significantly lower post dialytic plasma urea concentration with the diacetate membrane, these for phosphate did not reach statistical significance. These data suggest that the use of the diacetate membrane potentially offer clinical benefit. However, whether 16% of phosphate removal could improve clinical control of serum phosphate levels will need further investigation.     

Comparative analysis of procoagulatory activity of haemodialysis, haemofiltration and haemodiafiltration with a polysulfone membrane (APS) and with different modes of enoxaparin anticoagulation.

BACKGROUND: Treatment modalities of renal replacement therapy differ in their diffusive and convective mass transfer characteristics. It was the goal of this study to clarify whether an increase in convective mass transfer as performed with haemofiltration (HF) and haemodiafiltration (HDF) in comparison with high-flux haemodialysis (HD) is associated with an alteration in procoagulatory activity or with complement activation. METHODS: Ten stable chronic HD patients were monitored during 120 treatments in a randomized cross over design. A high-flux polysulfone dialyser (APS 900) was used for high-flux HD, pre-dilution HF and pre-dilution HDF. Constant flow of on-line substitution fluid for HF and HDF was 200 ml/min. The low molecular weight heparin (LMWH) enoxaparin was used for anticoagulation (i) as single bolus (50 IU/kg body weight, median 3700 IU) and (ii) as bolus of 1200 IU followed by a median continuous dose of 400 IU/h. Blood samples were collected before the LMWH bolus, after 10 min, 60 min, 120 min and at the end of treatment in venous and arterial blood lines to determine antiXa activity, thrombin-antithrombin-III complex (TAT), D-dimer and C5a generation. RESULTS: Net ultrafiltration did not significantly differ between HD, HF and HDF but total ultrafiltration in HF and HDF far exceeded total ultrafiltration in HD. With conditions of single bolus, or bolus and continuous anticoagulation with enoxaparin, after comparable treatment times (median duration 4.25 h), TAT and D-dimer generation at identical anti-Xa levels revealed significantly higher coagulation activity during HF and HDF, compared with high-flux HD as assessed by comparative area under the curve (AUC) analysis. Plasma concentration of C5a in venous bloodlines did not significantly differ during HD, HF and HDF. CONCLUSION: A higher convective mass transfer during HF and HDF, in comparison with high-flux HD caused by a greater total ultrafiltration volume was associated with increased procoagulatory activity in the extracorporeal circuit. Molecular markers assessing the activation of coagulation are appropriate to adjust the anticoagulation regime to high UF volumes in order to minimize bleeding risk and optimize patency of the extracorporeal circuit.     

Serum levels of beta-trace protein and its association to diuresis in haemodialysis patients.

BACKGROUND: Beta-trace protein (BTP) has been proposed as an alternative endogenous marker of the glomerular filtration rate. However, possible determinants of BTP in ESRD patients undergoing regular renal replacement therapy have not been evaluated. METHODS: Serum levels of BTP, beta-2-microglobulin, creatinine and urea were analysed before and after dialysis treatment in 73 patients [haemodialysis (HD) n=52; haemodiafiltration (HDF) n=21]. Patients were categorized into four groups with residual diuresis (RD)<0.5 l/day (group 1; n=24), 0.5-1 l/day (group 2; n=18), 1.1-1.5 l/day (group 3; n=12) and >1.5 l/day (group 4; n=19). Subsequently RD was compared to pre-treatment levels of BTP. RESULTS: HD treatment did not affect BTP serum levels [pre-treatment 8.1+/-4.1 mg/l (mean+SD) vs post-treatment 7.7+/-4.1 mg/l; -0.6 +/- 16.1%; ns]. However, in 6 out of 21 patients undergoing HDF BTP levels were reduced by more than 20%. Overall, the resulting decrease in serum concentration was minuscule (9.6+/-6.2 vs 8.3+/-4.9 mg/l; -14+/-21.9%; P=0.03). BTP serum levels were tightly associated to RD of the four groups. Comparison of BTP levels showed significant differences between patients of groups 1 vs 3 and 4 as well as 2 vs 4. CONCLUSIONS: BTP serum levels may serve as a surrogate marker for residual renal function since HD and HDF do not exert clinical relevant alterations on them. Furthermore, BTP serum concentrations appear strongly associated to RD.     

High membrane transport status on peritoneal dialysis is not associated with reduced survival following transfer to haemodialysis.

BACKGROUND: High transporter status is associated with reduced survival of patients receiving peritoneal dialysis (PD). This may be due primarily to the development of complications related to the PD process, in which case the survival disadvantage may not persist following transfer to haemodialysis (HD). In this study, we aimed to assess the impact of peritoneal membrane transporter status on patient survival and the likelihood of return to PD following transfer from PD to HD. METHODS: The Australia and New Zealand Dialysis and Transplant (ANZDATA) Registry was searched to identify all patients between 1 April 1999 and 31 March 2004 who had received PD and subsequently transferred to HD, in whom an incident 4 h dialysate: plasma creatinine ratio was recorded. A Cox proportional hazards model was used to identify factors significantly associated with patient and technique survival after commencement of HD. RESULTS: A total of 918 patients were included in the analysis. On multivariate Cox regression analysis there was no difference in survival between transport groups relative to the reference group of low average transporters (adjusted hazard ratio (HR) 0.71, 95% CI 0.42-1.19, P = 0.19, HR 0.94, 95% CI 0.63-1.38, P = 0.73 and HR 0.24, 95% CI 0.06-1.01, P = 0.051 for high, high average and low transporter groups, respectively). Significant predictors of mortality were duration of PD more than 22 months (HR 2.32, 95% CI 1.24-4.33, P = 0.01), increasing age, late referral to a nephrologist and a history of diabetes mellitus. The likelihood of returning to PD was increased if initial PD technique failure was due to mechanical complications compared with all other causes of failure [HR 3.65 (95% CI 2.78-4.79) P < 0.001] and decreased with higher body mass index [HR 0.97 per kg/m(2) (95% CI 0.94-0.99), P = 0.01] and the 4 h dialysate: plasma creatinine ratio considered as a continuous variable [4 h D:P Cr; HR 0.32 per unit (95% CI 0.12-0.89), P = 0.03]. CONCLUSIONS: The survival disadvantage associated with high peritoneal membrane transport status during PD treatment does not persist following transfer to HD. Early transfer to HD may be beneficial in this patient group.     

Effect of high-flux dialysis on the anaemia of haemodialysis patients.

BACKGROUND: Anaemia is one of the major clinical characteristics of patients with chronic renal failure, and has a considerable effect on morbidity and mortality. Adequate dialysis is of paramount importance in correcting anaemia by removing small and medium-sized molecules, which may inhibit erythropoiesis. However, high-molecular-weight inhibitors cleared only by means of highly porous membranes have also been found in uraemic serum and it has been claimed from uncontrolled studies that high-flux dialysis could improve anaemia in haemodialysis patients. METHODS: We therefore planned this multicentre randomized controlled trial with the aim of testing whether the use of a large-pore biocompatible membrane for a fixed 12-week follow-up improves anaemia in haemodialysis patients in comparison with the use of a conventional cellulose membrane. Eighty-four (5.3%) of a total of 1576 adult haemodialysed patients attending 13 Dialysis Units fulfilled the entry criteria and were randomly assigned to the experimental treatment (42 patients) or conventional treatment (42 patients). RESULTS: Haemoglobin levels increased non-significantly from 9.5+/-0.8 to 9.8+/-1.3 g/dl (dP=0. 069) in the population as a whole, with no significant difference between the two groups (P:=0.485). Erythropoietin therapy was given to 32/39 patients (82%) in the conventional group, and 26/35 (74%) in the experimental group (P:=0.783) with subcutaneous administration to 26/32 patients in conventional and to 23/26 patients in experimental group, P:=0.495. Dialysis dose (Kt/V) remained constant in both groups (from 1.30+/-0.17 to 1.33+/-0.20 in the conventional group and from 1.28+/-0.26 to 1.26+/-0.21 in the experimental group, P:=0.242). Median pre- and post-dialysis beta(2)-microglobulin levels remained constant in the conventional group (31.9 and 34.1 mg/dl at baseline) and decreased in the experimental group (pre-dialysis values from 31.1 to 24.7 mg/dl, P:=0.004 and post-dialysis values from 24.8 to 20.8 mg/dl, P:=0.002). Median erythropoietin doses were not different at baseline (70 IU/kg/week in conventional treatment and 90 IU/kg/week in experimental treatment, P:=0.628) and remained constant during follow-up (from 70 to 69 IU/kg/week in the conventional group and from 90 to 91 IU/kg/week in the experimental group, P:=0.410). Median erythropoietin plasma levels were in the normal range and remained constant (from 12.1 to 12.9 mU/ml in the conventional group and from 13.2 to 14.0 mU/ml in the experimental group, P:=0.550). CONCLUSIONS: This study showed no difference in haemoglobin level increase between patients treated for 3 months with a high-flux biocompatible membrane in comparison with those treated with a standard membrane. When patients are highly selected, adequately dialysed, and have no iron or vitamin depletion, the effect of a high-flux membrane is much less than might be expected from the results of uncontrolled studies.     

Pyridinium crosslinks in patients on haemodialysis and continuous ambulatory peritoneal dialysis

BACKGROUND: The urine excretion of the pyridinium crosslinks of collagen,pyridinoline (PYD) and deoxypyridinoline (DPD) closely reflectbone resorption and their assay has been used as specific markersof mature collagen turnover. The aims of this study were toevaluate the use of these markers to predict the severity ofosteodystrophy in patients with chronic renal failure. METHODS: Using an isocratic ion-paired reverse-phase high-performanceliquid chromatography, PYD and DPD were determined in the serum,urine and dialysate of 48 patients with chronic renal failureundergoing haemodialysis (n=28) or continuous ambulatory peritonealdialysis (n=20). Nineteen apparently healthy subjects were studiedas controls. RESULTS: In all groups, serum and urine crosslinks excretion showed poorcorrelation with age. In the patients urine PYD/creatinine andDPD/creatinine were significantly (P0.03 and 0.001 respectively)higher than normal; urine PYD and DPD levels were highly correlatedwith each other (r=0.98) and with serum PTH (r=0.84 and 0.83respectively). The mean (SD) predialysis serum PYD, 269 (334)nmol/l, was significantly (P0.003) elevated compared with normalpatients, 4.1 (0.6) and pre-dialysis serum DPD was 82.9 (93.7)nmol/l. DPD was below the detection limit of the assay in normalsera. In the patients postdialysis decreases in serum PYD andDPD were statistically significant (P<0.0002 and P<0.0007respectively). PYD and DPD were found in the dialysate of patientson haemodialysis as well as 24-h dialysate in patients on CAPD.Dialysate PYD and DPD were highly correlated with each other(r=0.80) and with dialysate creatinine (r=0.76 and r=0.62 respectively).In the patients, the mean serum, urine and dialysate PYD andDPD increased with the duration on dialysis. These findingsconfirm that metabolic bone disease increases in patients withduration of chronic renal failure. CONCLUSION: Estimation of serum crosslinks levels has potential as an additionaltool in the diagnosis and monitoring of renal osteodystrophy.The ability to determine crosslink levels in serum and dialysateshould be particularly useful in patients who are unable toproduce urine.     

Encephalopathy in patients on continuous ambulatory peritoneal dialysis and patients on chronic haemodialysis.

A group of 121 patients, 22 with a preterminal chronic renal insufficiency (PCRI), 74 on chronic haemodialysis (CHD), and 25 on continuous ambulatory peritoneal dialysis (CAPD), was evaluated by means of neurophysiological and neuropsychological studies to detect signs of central nervous system dysfunction. CHD patients were studied the day before dialysis treatment. In each patient the neurophysiological and neuropsychological studies were performed on the same day. The same overall result emerged from the neurophysiological and neuropsychological studies: all three patient groups showed significant deviations from the values obtained from a healthy reference group, whereas no differences were found between the three patient groups. Biochemical variables (a.o. PTH, Al, PO4) showed inconsistent or only minor correlations with the encephalopathic parameters. Apparently traditional biochemical variables are not a reliable measure to safeguard renal patients from neurotoxic damage. With respect to central nervous system dysfunction CAPD appears to be as 'safe' as CHD.     

Effect of dialyser membrane pore size on plasma homocysteine levels in haemodialysis patients.

BACKGROUND: Hyperhomocysteinaemia is a putative risk factor for atherothrombotic cardiovascular disease in the haemodialysis population. High-dose vitamin B therapy does not entirely normalize elevated plasma total homocysteine (tHcy) levels in haemodialysis patients. Alternative therapies to reduce tHcy further are therefore required. Modifications of the dialysis regimen may result in a better removal of Hcy. We examined the effect of dialyser membrane pore size on tHcy levels in vitamin-replete chronic haemodialysis patients. METHODS: Forty-five haemodialysis patients were dialysed during 4 weeks with a low-flux, a high-flux and a super-flux membrane, in random order. Pre-dialysis tHcy was determined at baseline and every 4 weeks. In 18 patients, plasma tHcy before and after dialysis and dialysate tHcy concentrations were measured. RESULTS: Pre-dialysis tHcy decreased significantly during 4 weeks super-flux dialysis (-14.6 +/- 2.8%), whereas it remained stable during high-flux (+0.5 +/- 2.4%) and low-flux dialysis (+1.7 +/- 3.2%). The homocysteine reduction ratio was not different for the three membranes: 0.39 +/- 0.03 for the super-flux, 0.47 +/- 0.02 for the high-flux and 0.39 +/- 0.02 for the low-flux dialyser. The amount of Hcy recovered in the dialysate during a single dialysis session was also similar: 117.5 +/- 3.6 micro mol during super-flux, 95.3 +/- 11.5 micro mol during high-flux and 116.5 +/- 11.6 micro mol during low-flux dialysis. CONCLUSION: Super-flux dialysis significantly lowers tHcy in chronic haemodialysis patients. Improved removal of middle-molecule uraemic toxins with inhibitory effects on Hcy-metabolizing enzymes, rather than better dialytic clearance of Hcy itself, may explain the beneficial effect of the super-flux membrane.     

Plasma ghrelin levels in patients undergoing haemodialysis and peritoneal dialysis.

BACKGROUND: Ghrelin has been characterized as a relevant physiologic regulator of appetite and body weight in humans. However, the potential relationships between ghrelin levels, inflammation and malnutrition in dialysis patients have not been adequately studied. METHODS: We used a cross-sectional design to study 20 haemodialysis (HD) and 21 peritoneal dialysis (PD) patients, and compared their plasma ghrelin (PGhr) levels with that of an age-matched control group. We also explored correlations between ghrelin and selected hormonal, renal adequacy, nutritional and inflammation markers in both groups. RESULTS: PGhr levels were higher in HD (median 119.8 pg/ml, range 71.1-333.7, P = 0.001) and PD (99.3, range 45.8-578.5, P = 0.045) patients than in healthy controls (78, range 29-158) (HD vs PD, not significant). Ghrelin levels were strongly and inversely correlated with age (r = -0.46, P = 0.02 for patients; r = -0.61, P = 0.001 for controls). Except for a positive correlation between ghrelin and growth hormone (r = 0.48, P = 0.002), univariate analysis failed to detect associations between PGhr and the measured hormonal values, renal adequacy, nutritional indicators and markers of inflammation. However, multivariate analysis revealed significant inverse correlations between PGhr levels and nutritional markers, including subjective global assessment (P = 0.013), albumin (P = 0.001), transferrin (P = 0.01) and protein nitrogen appearance (as an estimate of protein intake) (P = 0.035), after controlling for the confounding effect of age. CONCLUSIONS: PGhr levels were moderately and similarly increased in patients undergoing HD and PD. Age was a strong determinant of PGhr levels, both in uraemic patients and in healthy controls. Dialysis adequacy, residual renal function and inflammation did not appear to influence ghrelin levels in these patients. The negative correlation between PGhr and nutritional markers suggests that low dietary intake causes increases in ghrelin secretion in dialysis patients.     

Lipoprotein (a) in patients on maintenance haemodialysis and continuous ambulatory peritoneal dialysis

Lipoprotein (a) concentrations and apoprotein (a) isoforms weremeasured in 99 haemodialysis and 79 peritoneal dialysis patientsand compared with a normal population. Peritoneal dialysis patientsdemonstrated a threefold and haemodialysis a twofold increasein median Lp(a) values compared to controls (P0.001). The peritonealdialysis group had significantly more patients with Lp(a) valuesgreater than 30 mg/dl compared to controls, (53% versus 22%P0.001). In addition both patient groups demonstrated significanthypertriglyceridaemia (P0.001), reduction in HDL (P0.001) andelevation of the cholesterol/HDL ratio (P0.001) compared withcontrols. Peritoneal dialysis patients also demonstrated significanthypercholesterolaemia (P0.003). Lipoprotein (a) concentrations are considerably elevated inpatients on maintenance dialysis and this occurs in additionto the typical lipoprotein disturbances. This elevation mayincrease vascular risk, particularly in the peritoneal dialysisgroup who also have hypercholesterolaemia and reduced HDL.