Vitamin D status in patients with recurrent kidney stones.

Data regarding the prevalence of 25-hydroxyvitamin D (25(OH)D) insufficiency in patients with nephrolithiasis, and the effects of vitamin D supplementation on parathyroid hormone (PTH) are few and conflicting. In this article, we examined the prevalence of vitamin D insufficiency and deficiency in 236 recurrent kidney stone formers and the correlation of vitamin D levels with other parameters of stone formation. The prevalent stone composition was calcium oxalate (80.4%) and uric acid (16.45%). One third of stone formers had vitamin D insufficiency and a quarter of them high PTH levels (PTH >7.5 pmol/l) with normal serum (total and ionized) calcium values. Predictor of high PTH was low 25(OH)D level (r = 0.989, r(2) = 0.977, p < 0.001). Stone formers with hypercalciuria had higher 25(OH)D values (72.26 ± 4.21 vs. 59.29 ± 1.76, p = 0.0013) compared to stone formers with urine calcium within normal ranges. Further studies are needed in order to better define the consequences of vitamin D insufficiency and to evaluate the impact of the therapeutic interventions in this cohort.

Normocalcemic hyperparathyroidism in patients with recurrent kidney stones: a disease entity or vitamin D deficiency?

This retrospective data analysis was undertaken to examine the biochemical differences between renal stone formers with normocalcemic hyperparathyroidism (NHPT) and those with normal parathyroid hormone (PTH) levels. Our goal was to ascertain whether 25-hydroxyvitamin D (25(OH)D) status related to PTH levels in this patient cohort. Our findings among 74 patients with NHPT indicate that stone formers with NHPT had significantly lower 25(OH)D levels compared to 192 controls (p = 0.0001) and that 25(OH)D is positively correlated with 1,25-dihydroxyvitamin D values (R = 0.736, p = 0.015). Sequential measurements (after 3 - 5 years), among 11 patients with NHPT who did not receive vitamin D (VitD) preparations, showed a significant increase in urinary calcium (3.43 ± 1.96 vs. 5.72 ± 3.95, p = 0.0426) without a significant change in PTH levels. VitD supplementation, to 3 patients resulted in significant PTH decrease (11.8 ± 1.8 vs. 9.8 ± 1.3, p = 0.003). Prospective studies are needed to confirm the role of vitamin supplementation in renal stone formers with NHPT.

Aging and physiological changes of the kidneys including changes in glomerular filtration rate.

In addition to the structural changes in the kidney associated with aging, physiological changes in renal function are also found in older adults, such as decreased glomerular filtration rate, vascular dysautonomia, altered tubular handling of creatinine, reduction in sodium reabsorption and potassium secretion, and diminished renal reserve. These alterations make aged individuals susceptible to the development of clinical conditions in response to usual stimuli that would otherwise be compensated for in younger individuals, including acute kidney injury, volume depletion and overload, disorders of serum sodium and potassium concentration, and toxic reactions to water-soluble drugs excreted by the kidneys. Additionally, the preservation with aging of a normal urinalysis, normal serum urea and creatinine values, erythropoietin synthesis, and normal phosphorus, calcium and magnesium tubular handling distinguishes decreased GFR due to normal aging from that due to chronic kidney disease.

Diabetic patients on peritoneal dialysis.

During the past two decades, a number of studies have tried to evaluate the clinical status of dialyzed diabetic patients and the factors that may affect their outcomes. However, only a small number of diabetic patients on peritoneal dialysis (PD) have been followed for over 5 years, which is largely because of the presence of various comorbid conditions at the start of dialysis, the coexisting, far-advanced, target-organ damage that may gradually progress during the course of dialysis and limit the long-term survival on PD. On the contrary, among renal replacement therapies, survival of diabetic patients undergoing either PD or hemodialysis (HD) is probably similar, while diabetic patients on PD and HD have a lower actuarial survival than nondiabetic counterparts. This paper reviews our experience and the literature concerning the long-term outcome of diabetic patients on PD.

Sources of variation in estimates of lean body mass by creatinine kinetics and by methods based on body water or body mass index in patients on continuous peritoneal dialysis.

OBJECTIVE: We identified factors that account for differences between lean body mass computed from creatinine kinetics (LBM(cr)) and from either body water (LBM(V)) or body mass index (LBM(BMI)) in patients on continuous peritoneal dialysis (CPD). DESIGN: We compared the LBM(cr) and LBM(V) or LBM(BMI) in hypothetical subjects and actual CPD patients. PATIENTS: We studied 439 CPD patients in Albuquerque, Pittsburgh, and Toronto, with 925 clearance studies. INTERVENTION: Creatinine production was estimated using formulas derived in CPD patients. Body water (V) was estimated from anthropometric formulas. We calculated LBM(BMI) from a formula that estimates body composition based on body mass index. In hypothetical subjects, LBM values were calculated by varying the determinants of body composition (gender, diabetic status, age, weight, and height) one at a time, while the other determinants were kept constant. In actual CPD patients, multiple linear regression and logistic regression were used to identify factors associated with differences in the estimates of LBM (LBM(cr)LBM(V). The differences in determinants of body composition between groups with high versus low LBM(cr) were similar in hypothetical and actual CPD patients. Multivariate analysis in actual CPD patients identified serum creatinine, height, age, gender, weight, and body mass index as predictors of the differences LBM(V)-LBM(cr) and LBM(BMI)-LBM(cr). CONCLUSIONS: Overhydration is not the sole factor accounting for the differences between LBM(cr) and either LBM(V) or LBM(BMI) in CPD patients. These differences also stem from the coefficients assigned to major determinants of body composition by the formulas estimating LBM.

Thirty-six Hippocratic aphorisms of nephrologic interest.

In this article, we discuss the nephrologic content within Hippocrates' Aphorisms. Although similar attempts have taken place ever since antiquity, we believe that in each era new insights may be gained by examining the aphorisms through the prism of current medical knowledge. Of the 400 aphorisms in the Hippocratic text, we discuss the 36 that we consider to be most relevant to nephrology. We conclude that these aphorisms support the concept of Hippocrates as the "Father of Clinical Nephrology."

Association between pulse pressure and mortality in patients undergoing peritoneal dialysis.

BACKGROUND: Pulse pressure has been shown to be associated with adverse outcomes in the general population and in patients on hemodialysis (HD). However, the significance of pulse pressure has not been studied in peritoneal dialysis (PD) patients. This study examined the association between pulse pressure and mortality in patients undergoing chronic PD. METHODS: All patients aged 18 years or older that commenced PD between 1 January 2000 and 31 December 2005 at the University Health Network, Toronto, were included. The association between pulse pressure and mortality was assessed using the Cox proportional hazards model. RESULTS: A total of 306 patients were included in the study. Mean pulse pressure of the study cohort was 56.8 +/- 17.8 mmHg. Age and diabetes were significant predictors of elevated pulse pressure (p < 0.001). After adjusting for the level of systolic blood pressure and other demographic and clinical parameters, multivariable Cox proportional hazards modeling showed a direct and consistent association between pulse pressure and death risk. Each increment of 1 mmHg in pulse pressure was associated with a 2.7% increased hazard of all-cause death [95% confidence interval (CI) 1.001 - 1.054, p = 0.039] and a 4.1% increase in risk for cardiovascular mortality (hazard ratio 1.041, 95% CI 1.003 - 1.081; p = 0.035). CONCLUSION: Elevated pulse pressure is associated with an increased risk of all-cause and cardiovascular death in patients on PD. Recognition of this characteristic as an important predictor of mortality suggests that one goal of antihypertensive therapy in PD patients should be to decrease elevated pulse pressure.

The variability in ultrafiltration achieved with icodextrin, possibly explained.

BACKGROUND: A recent study by Jeloka et al. (Perit Dial Int 2006; 26:336-40) highlighted the high variability in maximum ultrafiltered volume (UF(max)) and the corresponding dwell time (t(max)) obtained using 7.5% icodextrin solution. We aimed to pinpoint the possible sources of this phenomenon by simulating the icodextrin ultrafiltration (UF) profiles according to the three-pore model of peritoneal transport. METHOD: The individual UF time courses observed in the study by Jeloka et al. (n = 29) were first characterized by linear and quadratic regression. We were then able to identify four main patterns. These were then adapted to UF profiles generated by the three-pore model by systematically altering the values of some model parameters, namely, the mass transfer area coefficient (MTAC or PS) for icodextrin/glucose, the peritoneal UF coefficient (LpS), the plasma colloid osmotic pressure gradient (DeltaPi), and the macromolecular clearance out of the peritoneal cavity (Cl(LF)). RESULTS: Modifications in the PS values caused only marginal variations in UF(max) and t(max), while more significant changes were produced by altering LpS and Cl(LF). However, far more evident was the importance of changes in DeltaPi. In fact, lowering DeltaPi to 14 mmHg caused a steady increase in UF with 10 - 14 hour dwells. On the contrary, the UF profiles became nearly "flat" when DeltaPi was increased to 30 mmHg. The parallel shifts induced by altering icodextrin metabolite concentrations did not markedly influence UF(max) or t(max). CONCLUSION: The UF pattern in icodextrin dwells seem to be mainly determined by the plasma colloid osmotic pressure, while only moderate changes can be seen with alterations in LpS and Cl(LF). The result is not completely unexpected considering that icodextrin acts by inducing a strong colloid osmotic gradient. A number of clinical studies would be needed, however, in order to prove this hypothesis.

Elderly diabetic patients on peritoneal dialysis.

Diabetes mellitus is the fastest-growing cause of end-stage renal disease (ESRD) among patients requiring renal replacement therapy (RRT). While diabetes mellitus has become the leading cause of ESRD, the number of elderly patients who need dialysis has grown almost exponentially. Most elderly patients with diabetes are treated with hemodialysis; only a small percentage are treated with peritoneal dialysis (PD). Elderly PD patients with diabetes have a lower survival rate than do nondiabetic patients and younger diabetic patients, perhaps because of the increased comorbidity seen in diabetic patients at dialysis initiation. Also, diabetic patients on RRT are at higher risk of developing de novo cardiovascular disease, one of the major causes of mortality. In Canada, survival in elderly diabetic patients undergoing PD is similar to that in hemodialysis patients; in the United States, patients over 45 - 55 years of age with diabetes have experienced higher mortality on PD than on hemodialysis. It is important, however to emphasize that survival on PD in these elderly patients has greatly improved in recent years. Fluid volume expansion may be one of the reasons for the higher mortality in elderly diabetic patients in some countries; but overall, PD remains a viable form of long-term RRT for elderly diabetic patients with ESRD.

Assisted peritoneal dialysis: what is it and who does it involve?

Together with the obvious increase of elderly patients with end-stage renal disease (ESRD), utilization of peritoneal dialysis (PD) has declined since the mid-1990s in a number of countries--a decline that is particularly marked in this elderly ESRD population. A major obstacle that affects any dialysis modality in elderly patients is the greater disease burden than is seen in younger patients. However; this factor may be overcome if patients start PD with assistance provided by visiting helpers (nurses or others) or people at home, mostly family members. Assisted PD (aPD) is suitable for; but not limited to, elderly patients who are unable to perform PD for themselves at home. Important considerations of an assisted model of care include frequency of visits, type of health care, and tasks to be performed for the patient at home. Clinical experience worldwide shows that aPD offers acceptable survival for most elderly and disabled patients, with no significant difference in modality-related complications from those seen in self-performed PD. Elderly patients on aPD experience more frequent hospitalizations, with longer hospital stays. Costs of aPD vary from country to country, depending on the frequency of visits and on reimbursement policies. Most authors believe that aPD can be cost-effective when compared with in-center hemodialysis.

Use of ACE inhibitors or angiotensin receptor blockers and survival in patients on peritoneal dialysis.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitors have been shown to improve outcome in patients with renal failure not on dialysis therapy and patients on haemodialysis (HD). However, their effect on survival has not been studied in peritoneal dialysis (PD) patients. The present study examined the association between therapy with ACE inhibitor/ARB and mortality in patients undergoing chronic PD. METHODS: All patients who commenced PD between 1 January 2000 and 31 December 2005 at the University Health Network were included. Patients were grouped according to whether they had been treated with ACE inhibitor/ARB. They were followed up from the date of PD initiation until death, cessation of PD, transfer to other centres or to the end of the study (31 December 2006). RESULTS: A total of 306 patients were included in the study. One hundred and sixty-five were treated with ACE inhibitors/ARB (treated group) and 141 were not (untreated group). The treated group patients were younger (56.9 +/- 16.6 versus 62.3 +/- 17.8 years, P < 0.01) and more likely to have a history of hypertension than the untreated group. At the initiation of PD, systolic and diastolic blood pressures were higher in the treated than the untreated group (138.8 +/- 21.8 versus 128.6 +/- 22.4 mmHg, P < 0.001; 79.8 +/- 14.1 versus 74.5 +/- 12.5 mmHg, P = 0.001) and remained significantly higher during the follow-up (133.5 +/- 16.4 versus 125.1 +/- 16.7 mmHg; 77.3 +/- 9.8 versus 73.2 +/- 9.7 mmHg, both P < 0.001). The treated group had a significantly longer survival compared to the untreated group (log rank 19.191, P < 0.001). After adjusting for age, blood pressure and other demographic and clinical parameters, multivariable Cox proportional hazards modelling showed that the use of ACE inhibitor/ARB was associated with 62% reduced risk for death (HR 0.382, 95% CI 0.232-0.631, P < 0.001). CONCLUSION: In this retrospective analysis, ACE inhibitor/ ARB therapy was associated with a dramatically reduced mortality in patients on peritoneal dialysis independent of blood pressure and other clinical and demographic variables.

Comparison of peritoneal dialysis practice patterns and outcomes between a Canadian and a Chinese centre.

UNLABELLED: Objective. We compared patient characteristics, dialysis practice patterns and outcomes of peritoneal dialysis (PD) patients between one Chinese centre and one Canadian centre to determine whether observed differences in demographics and practices are associated with patient and technique survival. METHODS: This study included all patients who started on PD between 1 January 2000 and 31 December 2004 at the University Health Network, University of Toronto, Canada and Renji Hospital, Shanghai Jiao Tong University School of Medicine, China. They were followed up from the date of PD initiation until death, cessation of PD, transfer to other centres or to the end of the study (31 December 2006). RESULTS: We studied 496 patients, 256 from the Canadian centre and 240 from the Chinese centre. Canadian patients were older and more likely to have diabetes and cardiovascular comorbidities at the initiation of PD, while the Chinese patients had lower residual renal function (RRF). More Canadian patients were treated with APD, whereas all Chinese patients were on CAPD with a lower PD volume. Crude patient survival rates at 1, 2, 3 and 5 years were similar between the two centres: 90%, 79%, 72% and 61% for Canadian and 90%, 79%, 71% and 64% for Chinese patients, respectively. After adjustment for demographic and clinical variables, there is no significant difference in mortality between Chinese patients and Canadian patients. Age, cardiovascular disease, diabetes, RRF and serum albumin were independent predictors of patient survival. The death-censored technique survival rates were significantly lower among the Canadian patients compared to Chinese patients. Chinese patients showed a lower risk of technique failure (HR 0.491, 95% CI 0.269-0.898, P = 0.021) after adjustment for patient characteristics. Chinese centre, BMI, serum albumin and gender were independent predictors of technique survival. The average peritonitis rate was one episode every 36.1 patient-months in Canadian patients and one episode every 60.6 patient-months in their Chinese counterparts. CONCLUSION: Patient characteristics, dialysis practice patterns and outcomes vary between Canadian and Chinese patients. The variability in patient outcomes between these two centres indicates that further improvements may be possible in both centres. We have identified several areas for improving outcomes.

High peritoneal permeability is not associated with higher mortality or technique failure in patients on automated peritoneal dialysis.

BACKGROUND: Patients on continuous ambulatory peritoneal dialysis (CAPD) who have high small-molecule peritoneal transport have increased mortality. OBJECTIVE: To investigate the impact of baseline peritoneal transport characteristics on patient and technique survival in incident peritoneal dialysis (PD) patients, most of whom are on automated PD (APD), with the use of icodextrin. DESIGN: Retrospective observational cohort study. SETTING: A single PD unit. PATIENTS AND METHODS: 193 new patients that began PD between January 2000 and September 2004, and had an initial peritoneal equilibration test within 6 months of commencement of PD. Patients were divided into low (L), low average (LA), high average (HA), and high (H) peritoneal transport groups. Death-censored technique failure and patient survival were examined. RESULTS: Of the 193 patients, 151 (78.1%) were on APD or on APD with icodextrin or on CAPD with icodextrin. At the end of 1, 3, and 5 years, patient survival was 91%, 82%, and 67% in LA group; 95%, 77%, and 69% in HA group; and 96%, 71%, and 71% in H group. Technique survival was 100%, 90%, and 77% in LA group; 96%, 84%, and 72% in HA group; and 92%, 87%, and 77% in H group. High peritoneal permeability did not predict worse patient survival or technique failure, while age, diabetes, a lower glomerular filtration rate, and high body mass index (> or =30 kg/m(2)) were independent predictors of death. CONCLUSION: This study suggests that higher peritoneal transport is not a significant independent risk factor for either mortality or death-censored technique failure. The favorable outcome for high transporters in this study may be due to improved management of volume status by the increased use of APD and the use of icodextrin-based dialysis fluid.

Comparison between bicarbonate/lactate and standard lactate dialysis solution in peritoneal transport and ultrafiltration: a prospective, crossover single-dwell study.

OBJECTIVE: It has been proposed that biocompatible bicarbonate/lactate based (Bic/Lac), physiologic-pH peritoneal dialysis (PD) solutions will be beneficial in long-term PD. However, we do not yet have detailed knowledge concerning the comparative physiology of buffer transport for these new solutions and their impact on underlying peritoneal transport of solutes and ultrafiltration (UF). The purpose of this study was to investigate the profile of buffer handling and peritoneal membrane transport characteristics during a single dwell of the new Bic/Lac-based versus standard lactate-based (Lac) PD solution. METHODS: In this prospective crossover study, we compared a 25 mmol/L bicarbonate/15 mmol/L lactate buffered, physiologic pH, low glucose degradation product (GDP) solution (Physioneal; Baxter Healthcare, McGaw Park, Illinois, USA) with a standard lactate buffered, acidic pH, conventional solution (Dianeal; Baxter). 18 patients underwent two peritoneal equilibration tests (PETs) with 2.5% Dianeal and 2.5% Physioneal separated by 1 week. Buffer transport, mass transfer area coefficients (MTACs), solute transport, and UF were determined for the two PETs. All bags were weighed by a nurse before instillation and after drainage to assess the net UF in each dwell. RESULTS: 18 patients that met the inclusion criteria were enrolled in this study. Whereas intraperitoneal pH remained constant at 7.52 +/- 0.11 throughout the dwell with the Bic/Lac solution, pH was still in the acidic range with the Lac solution after 1 hour (7.29 +/- 0.13, p < 0.001); this difference disappeared after the second hour of dwell. The MTACs for creatinine (10.68 +/- 3.66 vs 10.73 +/- 2.96 mL/minute/1.73 m(2), p > 0.05) and urea (27.94 +/- 10.50 vs 27.62 +/- 6.95 mL/min/1.73 m(2), p > 0.05), for Bic/Lac versus Lac respectively, did not differ between these two solutions; transport of glucose and other solutes was also similar. However, after a 4-hour dwell with Bic/Lac solution, net UF was significantly lower than that observed with Lac solution (274.2 +/- 223.3 mL vs 366.1 +/- 217.3 mL, p = 0.026). CONCLUSIONS: Compared to standard Lac-based solution, Bic/Lac based, pH neutral, low-GDP solution avoids intraperitoneal acidity. Peritoneal mass transport kinetics are similar for small solutes. Net UF is significantly lower with Bic/Lac solution; the mechanism for this is unclear.

Unusually prolonged vitamin D intoxication after discontinuation of vitamin D: possible role of primary hyperparathyroidism.

A 77-year-old woman had taken 50,000 IU of vitamin D2 daily, instead of once weekly, for over 2 years. She developed severe hypercalcemia, and after stopping vitamin D, her serum 25-hydroxyvitamin D (25(OH)D) remained higher than 250 nmol/l for almost 2(1/2) years. Inappropriately high parathyroid (PTH) concentrations were particularly evident after serum calcium was suppressed to slightly above the reference range by the administration of intravenous pamidronate and prednisone. It seems that an underlying primary hyperparathyroidism that was masked initially by the hypercalcemia of vitamin D intoxication was responsible for the unusually prolonged half-life of 25(OH)D in the blood. After vitamin D2 had been stopped, the decline in serum 25(OH)D was unusually slow. In this unusual case, primary hyperparathyroidism probably prevented an appropriate increase in the vitamin D-catabolizing enzyme, 25(OH)D-24-hydroxylase, thereby slowing metabolic clearance of 25(OH) vitamin D.

Assisted peritoneal dialysis as a method of choice for elderly with end-stage renal disease.

In the last two decades, most developed countries have seen a continuous growth in the number of elderly patients with end-stage renal disease commencing renal replacement therapy. Despite the many advantages that peritoneal dialysis (PD) offers to elderly patients with ESRD, it is still underutilized in older patients. Older patients are much more vulnerable to the problems associated with aging, which may affect their level of independence and their long-term prognosis. Those patients have physiological changes related to aging and common health problems such as anxiety, depression, dementia, visual impairment, and cognitive impairment, all of which interfere with self-performing PD. Assistance with home-care nurses and assistance by a family member may overcome this problem. Some old but also more recent literature data justifies the idea that assisted PD may significantly contribute to increase the overall number of elderly patients who can be treated with PD at home. With assisted PD, free choice can be offered to patients with high comorbidity index who cannot perform their peritoneal exchanges by themselves. Automated peritoneal dialysis is the ideal treatment modality for elderly patients with end-stage renal disease who require assistance since this limits home-care nurse visits to only two a day. As expected, the elderly have a higher mortality rate than younger patients treated by assisted PD, but technique failure rate, overall peritonitis rate, and most quality-of-life (QoL) measures are comparable with those of younger patients. Peritoneal dialysis in nursing homes offers treatment for elderly patients without family support. In this regard, automated PD or nightly PD keeps the patient's daytime free for nursing home activities, increases socialization, and enables better rehabilitation that improves their QoL. Although withdrawal from dialysis is more frequent among nursing-home dialysis patients, this high discontinuation rate is not due to dialysis per se but rather to associated social and medical circumstances. Better communication between nursing staff and renal team is crucial for improving staff confidence and will contribute to higher utilization of PD in nursing homes.

Advantages of peritoneal dialysis in comparison to hemodialysis, in cardiac allograft recipients with end stage renal disease.

End stage renal disease is a serious complication in heart or heart-lung transplant recipients and is associated with high morbidity and mortality. The majority of these patients are currently treated with hemodialysis. Since there are no randomized control trials comparing hemodialysis to peritoneal dialysis in this patient population, the potential beneficial effects of peritoneal dialysis remain largely unknown. We compared the clinical outcome of such patients on peritoneal dialysis with another group on hemodialysis. Our results indicate that patients on peritoneal dialysis had fewer episodes of congestive heart failure, fluid overload and a lower overall hospitalization rate, despite having worse cardiac function than patients on hemodialysis.

Nephrogenic systemic fibrosis: an emerging entity.

Nephrogenic systemic fibrosis (NSF) is a progressive disorder which has been seen only in patients with chronic kidney disease. It is associated with fibrosis of the skin and connective tissue throughout the body. The skin thickens and becomes hard, rigid, and coarse, which severely restricts movement of the joints. It can also lead to widespread fibrosis of internal organs involving lungs, heart, diaphragm, esophagus, and skeletal muscle, and in some cases may lead to death. Based on case series reports and skin biopsy showing gadolinium (Gd) ions, NSF has been directly linked to Gd contrast exposure given during MRI/MRA. There are over 250 reported cases of NSF worldwide with hundreds still not reported or remaining undiagnosed. Symptoms of NSF appear within 2-75 days, with a mean of 25 days after exposure to Gd contrast. This disorder is not well understood, and more research is needed to obtain information about how Gd causes this condition. Currently there is no effective treatment, so prevention is the only way to avoid this serious illness.

Magnesium carbonate for phosphate control in patients on hemodialysis. A randomized controlled trial.

BACKGROUND: Magnesium salts bind dietary phosphorus, but their use in renal patients is limited due to their potential for causing side effects. The aim of this study was to evaluate the efficacy and safety of magnesium carbonate (MgCO(3)) as a phosphate-binder in hemodialysis patients. METHODS: Forty-six stable hemodialysis patients were randomly allocated to receive either MgCO(3) (n=25) or calcium carbonate (CaCO(3)), (n=21) for 6 months. The concentration of Mg in the dialysate bath was 0.30 mmol/l in the MgCO(3) group and 0.48 mmol/l in the CaCO(3) group. RESULTS: Only two of 25 patients (8%) discontinued ingestion of MgCO(3) due to complications: one (4%) because of persistent diarrhea, and the other (4%) because of recurrent hypermagnesemia. In the MgCO(3) and CaCO(3) groups, respectively, time-averaged (months 1-6) serum concentrations were: phosphate (P), 5.47 vs. 5.29 mg/dl, P=ns; Ca, 9.13 vs. 9.60 mg/dl, P<0.001; Ca x P product, 50.35 vs. 50.70 (mg/dl)(2), P=ns; Mg, 2.57 vs. 2.41 mg/dl, P=ns; intact parathyroid hormone (iPTH), 285 vs. 235 pg/ml, P<0.01. At month 6, iPTH levels did not differ between groups: 251 vs. 212 pg/ml, P=ns. At month 6 the percentages of patients with serum levels of phosphate, Ca x P product and iPTH that fell within the Kidney Disease Outcomes Quality Initiative (K/DOQI) guidelines were similar in both groups, whereas more patients in the MgCO(3) group (17/23; 73.91%) than in the CaCO(3) group (5/20, 25%) had serum Ca levels that fell within these guidelines, with the difference being significant at P<0.01. CONCLUSION: Our study shows that MgCO(3) administered for a period of 6 months is an effective and inexpensive agent to control serum phosphate levels in hemodialysis patients. The administration of MgCO(3) in combination with a low dialysate Mg concentration avoids the risk of severe hypermagnesemia.

Icodextrin produces higher ultrafiltration in diabetic than in non-diabetic patients on continuous cyclic peritoneal dialysis.

A preliminary report from our unit previously suggested that diabetic patients on continuous cyclic peritoneal dialysis (CCPD) have higher ultrafiltration (UF) with icodextrin than non-diabetic patients. To confirm this observation, we did a retrospective analysis of our patients (17 diabetic and 23 non-diabetic) who were on stable CCPD prescription using a long-day dwell with icodextrin. We collected daily UF data from these patients' records for 30 days. The two groups showed no significant difference with respect to age, gender, hemoglobin, serum albumin, peritoneal dialysis and icodextrin vintage, peritoneal membrane characteristics, CCPD prescription, and peritoneal and residual renal clearance. The overnight net UF achieved with the cycler with standard glucose dialysate was similar in the two groups (850+/-379 in diabetic vs 713+/-484 ml/day in non-diabetic, P=0.34). However, UF with icodextrin during the day dwell (14.8+/-0.8 h) was significantly higher in diabetics than non-diabetics (348+/-198 vs 137+/-311 ml/day, P=0.02). Our results show that icodextrin produces significantly higher UF in long-day dwell in diabetic ESRD patients on CCPD than in non-diabetic patients. The reason for this difference is not clear.