The Trio Trial - A Randomized Controlled Clinical Trial Evaluating the Effect of a Biocompatible Peritoneal Dialysis Solution on Residual Renal Function.

UNLABELLED: ♦ BACKGROUND AND OBJECTIVE: Residual renal function (RRF) correlates with mortality and morbidity rates in patients receiving peritoneal dialysis (PD). We examined the effect of a biocompatible PD solution (Gambrosol Trio; Gambro Lundia AB, Lund, Sweden) with lower concentrations of glucose degradation products on rates of decline in RRF. ♦ DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Incident patients at 2 centers in Canada and 1 in Hong Kong were randomized (by minimization) in an open-label parallel group trial to receive Gambrosol Trio or standard PD solution (Dianeal; Baxter Healthcare, Mississauga, Canada) for 2 years. Primary outcome was slope of RRF. Secondary outcomes were urine volumes, fluid and nutrition indices, PD and membrane characteristics, peritonitis rates, adverse events, and PD technique survival. ♦ RESULTS: Residual renal function declined by 0.132 mL/minute/1.73 m(2)/month in 51 patients allocated to biocompatible, and 0.174 mL/minute/1.73 m(2)/month in 50 patients allocated to standard PD solution (difference 0.042 mL/minute/1.73 m(2)/month, p = 0.001). Urine volume, body mass index, normalized protein catabolic rates, and fat mass were higher; total body water, peritoneal ultrafiltration, and D/P creatinine did not differ; and serum phosphate, rates of icodextrin, and automated cycler use were lower with Gambrosol Trio use. There were more peritonitis events with Gambrosol Trio use, while PD technique survival did not differ between groups. ♦ CONCLUSIONS: The use of the biocompatible PD solution Gambrosol Trio was associated with slower rates of decline in RRF, fluid and nutrition benefits, and increased peritonitis rates. TRIAL NUMBER: ISRCTN26252543.

Magnesium retards the progress of the arterial calcifications in hemodialysis patients: a pilot study.

BACKGROUND: The aim of the study was to evaluate the impact of magnesium (Mg) on the evolution of arterial calcifications in hemodialysis patients. PATIENTS AND METHODS: Seventy-two stable hemodialysis patients were randomly allocated to two groups: 36 administered a regimen containing magnesium carbonate plus calcium acetate as a phosphate binder (Mg group), while the rest 36 received calcium acetate alone (Ca group). The presence and the progression of arterial calcifications were evaluated in plain X-rays using a simple vascular calcification score. The duration of the follow-up period was 12 months. RESULTS: Thirty-two patients of the Mg group and 27 of the Ca group completed the study. The mean time average values of the biochemical laboratories did not differ between the two groups, except serum Mg: 2.83 + 0.38 in the Mg group versus 2.52 + 0.27 mg/dl in the Ca group, p = 0.001. In 9/32 (28.12 %) patients of the Mg group and in 12/27 (44.44 %) patients of the Ca group, the arterial calcifications were worsened, p = 0.276. Moreover, in 4/32 (15.6 %) patients of the Mg group and in 0/27 (0 %) patients of the Ca group, they were improved, p = 0.040. The multivariate logistic regression analysis revealed that serum magnesium was an independent predictor for no progression of the arterial calcifications, p = 0.047. CONCLUSIONS: Magnesium probably retards the arterial calcifications in hemodialysis patients. Further clinical studies are needed to clarify whether magnesium provides cardiovascular protection to this group of patients.

Hyponatremia in peritoneal dialysis: epidemiology in a single center and correlation with clinical and biochemical parameters.

BACKGROUND: Hyponatremia in peritoneal dialysis (PD) patients has previously been associated with water overload and weight gain, or with malnutrition and intracellular potassium depletion. Although there is a sizable literature about transmembrane sodium and water removal in PD, there are few reports about the incidence and characteristics of hyponatremia in the clinical setting. AIM: We evaluated the incidence and factors associated with hyponatremia in PD patients in a single PD unit. METHODS: We retrospectively evaluated the records of all patients (n = 198) who were treated with PD in the Home PD Unit of the University Health Network at Toronto General Hospital during 2010. We identified 166 patients who had a minimum follow-up of 60 days during 2010 and at least 2 consecutive sodium measurements at least a month apart. We examined baseline differences between patients who developed hyponatremia and those who did not, and clinical and biochemical factors that correlated with mean sodium values. In the 24 patients who developed hyponatremia, we examined paired differences between the normonatremic and hyponatremic periods. Finally, we investigated any possible correlations of change in serum sodium with clinical and biochemical characteristics before and during the hyponatremic period. RESULTS: The incidence of hyponatremia was 14.5%. In multivariate analysis, serum sodium correlated significantly and independently with residual renal function (RRF: r = 0.463, p = 0.0001) and negatively with the daily volume of instilled icodextrin (r = -0.476, p = 0.0001). Residual renal function was significantly lower in patients with hyponatremia than in those with normal serum sodium (1.97 ± 2.3 mL/min vs 4.31 ± 5.01 mL/min, p = 0.033). The mean paired difference in body weight was -1.113 kg and the median difference was -0.55 kg (range: -8.5 kg to +4.2 kg). Impressively, hyponatremia was not associated with an increase in body weight in most patients who developed this complication (13 of 16 for whom comparative weights were known). Moreover, the mean paired change in serum sodium (ΔNa) from normonatremia to hyponatremia was, contrary to our expectations, significantly correlated with a decrease in body weight (r = 0.584, p = 0.017). The ΔNa was also significantly correlated with serum potassium (r = 0.526, p = 0.008), the greatest drop in serum sodium being associated with lower serum potassium in the hyponatremic period, as predicted. CONCLUSIONS: Hyponatremia is seen more often than expected in a clinical setting. Serum sodium is strongly correlated with RRF, hyponatremia being associated with lower RRF. In patients who experienced hyponatremia, the fall in serum sodium was associated with a decrease, not an increase, in body weight and was correlated with serum potassium, suggesting that sodium and potassium depletion-and, by inference, malnutrition-may be important contributors in the clinical setting.

Peritoneal dialysis outcomes in a modern cohort of overweight patients.

BACKGROUND: The incidence of obesity is increasing both in the general population and in incident dialysis patients. While there is evidence that being overweight is associated with good outcomes in hemodialysis, the evidence in peritoneal dialysis (PD) patients is not very clear. We studied a modern cohort of PD patients to examine outcomes in large patients. METHODS: Forty-three patients who started PD, who weighed more than 90 kg at dialysis initiation, between January/2000 and June/2010 were matched with 43 control patients who weighed less than 90 kg. Detailed review of the charts was undertaken. RESULTS: The mean weight and body mass index of the wt < 90 kg group were 69.3 ± 11.3 kg and 25.0 ± 3.9 kg/m(2). The number of peritonitis episodes per year was 0.33 ± 0.6 (wt < 90 kg) and 0.82 ± 1.7 (wt ≥ 90 kg) (p = 0.26). The median time to first peritonitis showed a trend toward earlier peritonitis in larger patients [9.5 (4.3, 27) months in wt ≥ 90 kg, 19.1(7.9, 30.8) months in wt < 90 kg] but did not reach statistical significance (p = 0.12). Surprisingly, hernias and leaks were more common in the weight <90 kg group (44 vs. 18.6 % p = 0.02). There was no difference in total number of hospitalizations or the number of days hospitalized. Kaplan-Meier analysis of survival on PD showed no differences between the two groups (logrank p = 0.99). Cox regression analysis using age, race, cause of ESRD due to diabetes and Charlson comorbidity index as the covariates did not show weight to be associated with survival on PD. CONCLUSIONS: Large patients tend to do just as well on PD, with survival on PD being no different compared to individuals with lower weight and body mass index.

Glycemic control and survival in peritoneal dialysis patients with diabetes mellitus.

PURPOSE: The optimal target for glycated hemoglobin (HbA1c) has not been well defined in peritoneal dialysis (PD) patients with diabetes mellitus. METHODS: The objective of our study was to examine the predictive value of predialysis and time-averaged follow-up HbA1c values on technique and patient survival in diabetic PD patients treated in the Toronto General Hospital Home Peritoneal Dialysis Unit, between January 1, 2003 and December 31, 2008 with a median follow-up period of 30±23 months. RESULTS: Ninety-one patients (mean age 64±13 years-old) were included in this retrospective study. Patients were followed between 3 and 91 months (mean duration 30±23 months). During this period, 40 patients died. We found no statistically significant correlation between baseline predialysis HbA1c values and technique and patient survival. Time-averaged follow-up HbA1c in increments<6.5%, 6.5-8%, and >8% showed no significant survival difference among groups. CONCLUSIONS: There was no significant correlation of baseline and time-averaged follow-up HbA1c values with patient and PD technique survival.

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.

Variability in CKD stage in outpatients followed in two large renal clinics.

OBJECTIVE: Chronic kidney disease (CKD) is staged by glomerular filtration rate (GFR). CKD stages sometimes vary between routine office visits, and it is unknown if this impacts renal and patient survival separately from a cross-sectional CKD stage value. We quantified and categorized CKD stage variability in a large group of outpatients and correlated this with clinical and demographic features and with renal and patient survival. METHODS: All estimated GFRs were staged in the first observation period. CKD stages were then categorized as static, improving, worsening, or fluctuating. Logistic regression analysis was performed to identify clinical variables associated with CKD stage variability. Death and dialysis progression rates were then collected and analyzed using Cox proportional regression. RESULTS: During a 1.1-year observation period, 1,262 patients (mean age 71.25 years) had a mean 5 eGFR's. CKD stages were static in 60.4%, worsened in 14.4%, improved in 7.4%, and fluctuated in 17.2% of patients. Secondary analysis revealed heavy proteinuria and East Asian ethnicity to be negatively, and diabetes mellitus and previous acute kidney injury to be positively associated with improving CKD stages. Cox proportional regression of 902 patients analyzed 2.3 years later revealed a negative association with improving CKD stage and subsequent need for dialysis. CONCLUSIONS: CKD stage changed in 40% of 1,262 elderly patients when determined 5 times in just over 1 year. Improving CKD stage was the only variability pattern significantly associated with any of the clinical outcomes when assessed 2.3 years later, being unlikely to be linked with subsequent need for dialysis.

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.

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.

Home dialysis first: a new paradigm for new ESRD patients.

Patients with end-stage renal disease (ESRD) were treated with either in-center hemodialysis (ICH) or one of the modes of home-based dialysis (HBD)-- peritoneal dialysis (PD) or home hemodialysis (HHD). Home-based dialysis modes showed better outcomes than ICH (PD for the first 2-3 years and HHD for the long-term). Home PD has become more attractive with overnight cyclers for PD and the use of home helpers. Home dialysis (PD or HHD) offers a high quality of life and a high degree of independence and is financially attractive. This review will propose a paradigm shift in the initial form of dialysis offered to new patients with ESRD: instead of selecting between in-center dialysis and PD, patients after they are advised of the advantages of dialysis at home (either PD or HHD) should be offered a choice between dialysis at home (PD or HHD) or in hospital. We will review the advantages of home-based dialysis and the arguments for this simple but vital change in the process by which new patients requiring dialysis choose their treatment option.

Encapsulating peritoneal sclerosis: a single-center experience and review of the literature.

Encapsulating peritoneal sclerosis (EPS) is a serious and often fatal complication of long-term PD with severe malnutrition and poor prognosis. It causes progressive obstruction and encapsulation of the bowel. This retrospective study reviews our experience and that reviewed in the literature concerning EPS. It refers to a total of 1966 patients treated with chronic PD between 1974 and 2008. Twenty one of them (1.1%) developed EPS, with the incidence increasing with the duration of PD. Mean age of our patients with EPS was 43, ranging from 18 to 71 years, 8 were men and 13 women with a mean body mass index (BMI) of 21.6 kg/m(2). Only one patient had Type II diabetes, 15 patients had glomerular disease, and six of these 15 had an autoimmune disease such as Wegener's granulomatosis and SLE. Thirteen patients developed EPS while on PD, 7 within 2 years after transfer to HD, and only one after renal transplantation. However, 7 patients had a previous renal transplant before returning to PD and subsequently developing EPS. Interestingly, we did not observe more episodes of EPS after transplantation. In the patients who developed EPS, the peritonitis rate over the period of observation was 1/15.6 pt-months and was due to Staphylococcus aureus, coagulase-negative staphylococcus, Pseudomonas and fungi. A history of peritonitis was not a prerequisite for developing EPS, since one patient had no episodes of peritonitis and 4 had just one previous episode. Fifteen patients presented with peritonitis within 4 months before the diagnosis of EPS with particularly virulent micro-organisms such as S. aureus, Candida, Pseudomonas, Corynebacterium, and Peptostreptococcus. Eleven patients were treated with hypertonic dextrose solutions (4.25 g/dl of dextrose) and seven with icodextrin, indirectly suggesting problems with ultrafiltration. Nine of 21 patients were on beta-blockers. The diagnosis of EPS was made either surgically or radiologically with signs of small bowel obstruction in combination with severe malnutrition. Eleven of our patients (52%) had evidence of small bowel obstruction and 14 patients required total parenteral nutrition (TPN). Tamoxifen (10-20 mg daily) was started in 6 patients, 4 of whom are alive and 2 deceased 3 and 5 years after EPS was diagnosed. Of the 12 patients who were not given tamoxifen, 2 are alive and 10 died. No side effects of tamoxifen were reported. Only 7 of our patients (33%) died during the first year after the diagnosis of EPS. Currently, 4 patients are on HD and 3 have had a renal transplant. Six patients of the fourteen who underwent surgery (42.8%) died within the first 6 months after operation and five died after an average of 6.6 years, mostly due to cardiovascular causes, three are still alive. As EPS becomes more prevalent with longer duration of PD, large multicenter prospective studies are needed to establish its incidence and identify risk factors, therapeutic approach, and prognosis.

Update on potential medical treatments for encapsulating peritoneal sclerosis; human and experimental data.

Encapsulating peritoneal sclerosis (EPS) is an infrequent but serious complication of peritoneal dialysis (PD). The pathogenesis is unknown but speculation is ongoing. The current management of EPS focuses on prevention and treatment of the inflammatory and fibrotic changes at the level of the peritoneal membrane with immunosuppressive and antifibrotic agents, respectively. This article reviews the currently available human and animal data on potential agents to prevent and/or treat EPS. We propose a strategy for early diagnose EPS in an attempt to avoid the development of the full-blown and potentially life-threatening clinical syndrome of EPS. Future research should focus on studying potential prophylactic and therapeutic agents in humans in large, multicenter, randomized trials but also on early detection of EPS in the inflammatory phase by means of biomarkers and the establishment of a composite EPS score.

Two icodextrin exchanges per day in peritoneal dialysis patients with ultrafiltration failure: one center's experience and review of the literature.

BACKGROUND: At present, only one exchange of an icodextrin-based solution is recommended to increase peritoneal ultrafiltration (UF) during long-dwell exchanges in peritoneal dialysis (PD) patients with impaired UF. AIM: To review our experience with two icodextrin exchanges per day on net UF and body weight in PD patients with poor UF. METHODS: Data were analyzed on nine patients with poor UF on chronic PD who were given two icodextrin exchanges per day for 6 months and had various clinical and biochemical parameters assessed monthly. RESULTS: Administration of icodextrin twice daily reduced the body weight in six of nine patients by an average of 2.9 ± 1.2 kg, a reduction that was maintained throughout the study; two patients gained 0.5 kg; and, in one patient, the measurements were inadequate. Mean blood pressure was reduced. Mean serum creatinine increased slightly. Serum sodium levels decreased from a mean baseline level of 134 ± 3 to 132 ± 4 mmol/L at three and six months. Among the diabetics in this group, average daily insulin requirements were 44 ± 35 units/day at baseline and 40 ± 23 units/day after 6 months. Hb1Ac levels remained stable throughout the study period. CONCLUSION: The use of two icodextrin exchanges per day reduced body weight in six of the nine patients and appeared to be safe. Long-term prospective studies are needed to assess the contribution of twice-daily icodextrin to the management of peritoneal dialysis patients with ultrafiltration failure and its long-term safety.

Discordant PD catheter and effluent culture results. The limited clinical relevance of culturing PD catheters.

OBJECTIVES: To determine if discordance in culture results between the effluent and the tip of the peritoneal catheter had an effect on outcome in patients whose peritoneal dialysis (PD) catheter was removed mostly for nonresolving peritonitis. Reasons for and outcomes of PD catheter removal were also analyzed. METHODS: We retrospectively reviewed the charts of all PD patients with recent peritonitis for which the PD catheter was removed between 1 January 2003 and 30 April 2009. Data including basic demographics, the organism isolated from effluent and from the PD catheter, reason for catheter removal, duration of hospitalization, and development of intra-abdominal collection were extracted as well as mortality within 8 weeks post removal and return to PD after catheter removal. RESULTS: Fungal peritonitis was the most common reason for PD catheter removal. 20% of the patients developed an intra-abdominal collection. Mortality related to PD catheter removal was low (3/53; 5.6%). The patients (n =53) were divided into 3 groups: group 1 (n = 20) had the same culture result of effluent and catheter tip; group 2 (n = 19) had a negative culture of the catheter tip; and group 3 (n = 14) had different organism(s) growing from effluent and catheter tip. We found no remarkable differences in duration of PD, catheter age, peritonitis rate, or mortality. Patients in group 1 had significantly more fungal peritonitis than the other 2 groups. In only 4 of the 53 patients (7.5%), the anti-infectious management was changed according to the catheter culture result. CONCLUSIONS: Discordant results between catheter tip culture and effluent culture did not have a significant impact on patient outcome. Sending PD catheters for culture has limited clinical importance.

Dialysis modality choices among chronic kidney disease patients: identifying the gaps to support patients on home-based therapies.

BACKGROUND: Home dialysis is a cost-effective renal replacement strategy, which provides improved quality of life compared to conventional in-center hemodialysis (CHD). To date, most studies support the use of multidisciplinary chronic kidney disease (CKD) clinics to facilitate timely initiation of dialysis. This is an observational cohort study examining 486 patients with CKD over the period of 2001-2007 to ascertain potential demographic differences among patients transitioned to in-center versus home dialysis. SUBJECTS AND METHODS: From January 2001 to December 2007, 486 patients with CKD attended the multidisciplinary renal management clinic at the University Health Network in Toronto. RESULTS: One hundred and fifty-three of the 486 patients were initiated on renal replacement therapy [59 to center hemodialysis (CHD), 15 to home hemodialysis (HHD) and 79 to home peritoneal dialysis (PD)]. HHD patients were younger (48 ± 15 years) than those who selected CHD (62 ± 16 years) or PD (64 ± 16 years). Although the gender distribution was similar overall, the percentage of single males was higher in CHD versus home dialysis patients (29 vs. 15%, P < 0.05). There were no significant differences in other demographic, clinical and biochemical parameters at the time of dialysis initiation. Disinterest in home dialysis by patients and their families (25.4%) and lack of social support (12.1%) constituted the main barriers to home dialysis. Medical contraindications for home dialysis were present among 11% of the patients. Other less frequent barriers were inadequate space, communication barrier and inability to perform their own dialysis. CONCLUSIONS: Sixty-one percent of patients requiring dialysis chose a home dialysis modality. Patients' and their families' disinterest in home dialysis and lack of support (either perceived or actual) represented the major overall barriers to adoption of home dialysis.

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.

Glucoregulatory hormones and choice of osmotic agent in peritoneal dialysis.

OBJECTIVE: The present study was performed to explore the range of effects of amino acid-based peritoneal dialysis (PD) solutions on glucoregulatory hormones in comparison with an osmotically equivalent glucose-based solution. ♢ METHODS: 13 adult nondiabetic patients on PD underwent 2 peritoneal dwells of 2 hours' duration with either 1.5% dextrose solution or 1.1% amino acid solution. Serial sampling for glucoregulatory hormones was done throughout the duration of the dwell. ♢ RESULTS: Instillation of the 1.5% dextrose solution resulted in a modest change in plasma glucose, paralleled by a small increase in plasma insulin levels and plasma insulin-like growth factor (IGF-1). Plasma glucagon was not changed and plasma growth hormone level declined. Instillation of the 1.1% amino acid solution resulted in an increase in plasma glucose, plasma insulin, plasma glucagon, and plasma IGF-1. Plasma growth hormone level declined. Both solutions led to an increase in plasma norepinephrine but no changes were observed in epinephrine or dopamine. ♢ CONCLUSIONS: Our observations suggest that the mere replacement of glucose by amino acids in PD solutions does not necessarily imply "glucose sparing" from the perspective of induction of a glucoregulatory hormonal response because of the aminogenic stimulation of secretion of multiple hormones.

Glomerular filtration rate (GFR) estimated from serum creatinine predicts total (urine and peritoneal) creatinine clearance in patients on peritoneal dialysis.

OBJECTIVES: The aim of this study was to examine the accuracy of the Modification of Diet in Renal Disease (MDRD) equation and the Cockcroft and Gault formula (CCrCG) in predicting total creatinine clearance achieved by residual renal function plus peritoneal dialysis in patients on chronic peritoneal dialysis. METHODS: Total creatinine clearance was defined as peritoneal creatinine clearance (PCcr) plus the average of urine urea and creatinine clearances (cGFR). Correlation analysis and Bland-Altman plot were used to establish the degree of correlation and agreement between the estimations of creatinine clearance achieved by PCcr and the average of cGFR and estimated creatinine clearance based on serum creatinine by using either MDRD equation or the Cockcroft and Gault formula. RESULTS: In one hundred fifty-six measurements, mean clearances by [cGFR + PCcr], CCrCG and MDRD were: 7.9 ± 3.1, 10.6 ± 5.2 and 8.5 ± 4.9 ml/min/1.73 m(2), respectively. There was a good correlation between [cGFR + PCcr] and MDRD (r = 0.776, P < 0.05) and [cGFR + PCcr] and CCrCG (r = 0.735, P < 0.05). The mean MDRD was not significantly different from the mean clearance by [cGFR + PCcr] (difference 0.4 ± 2.9 ml/min/1.73 m(2), agreement limit -5.4-6.3 ml/min/1.73 m(2)). The CCrCG formula gave a larger difference from the mean [cGFR + PCcr] (2.8 ± 10.5 ml/min/1.73 m(2)) and a much wider agreement limit (-3.7-9.3 ml/min/1.73 m(2)). In male patients, MDRD formula provided an estimate of clearance that was similar to the mean [cGFR + PCcr] (7.9 ± 3.8 ml/min/1.73 m(2) vs. 8.2 ± 3.2 ml/min/1.73 m(2), respectively; difference 0.10 ± 1.9 ml/min/1.73 m(2), limits of agreement -3.9-3.7 ml/min/1.73 m(2)). By contrast, in female patients, the MDRD equation significantly overestimated the clearance (difference between mean estimated and mean measured clearance 1.4 ± 4.1 ml/min/1.73 m(2), limits of agreement -6.6-9.5 ml/min/1.73 m(2) P < 0.05). In conclusion, the GFR estimated by MDRD formula is similar to [cGFR + PCcr] especially in males. GFR by the CCrCG formula tended to overestimate the highest values of [cGFR + PCcr].