Beta-2 microglobulin in patients on peritoneal dialysis and hemodialysis

Serum beta 2 microglobulin (beta 2 mu) levels were determined in 62 patients on chronic dialysis, divided according to the type of dialysis--cuprophane hemodialysis, chronic ambulatory peritoneal dialysis (CAPD), or CAPD started after 76 +/- 47 months on cuprophane hemodialysis--and to residual urine output greater than 400 mL/day or less than 10 mL/day. In addition, for patients on CAPD, peritoneal excretion, peritoneal clearance, and urinary excretion of the protein were determined. In anuric patients serum beta 2 mu levels were significantly higher in HD than in CAPD. In patients with residual urine output, serum concentrations of the microprotein were similar in HD and in CAPD. Significant differences were observed in beta 2 mu serum levels and peritoneal clearances in patients switched to CAPD from hemodialysis as compared to those starting with CAPD. Peritoneal clearances of the microprotein was slightly and non-significantly greater in patients with urine output than in anuric patients.     

QT dispersion and signal-averaged electrocardiogram in hemodialysis and CAPD patients.

OBJECTIVE: The aim of this study was to compare QT dispersion (QTd) and signal-averaged electrocardiogram (SA-ECG) parameters that may predict risk of malignant arrhythmias in patients on hemodialysis (HD), on continuous ambulatory peritoneal dialysis (CAPD), and in controls. SETTING: Controlled cross-sectional study in a tertiary-care setting. PATIENTS: 28 HD (M/F 18/10; mean age 32 +/- 9 years), 29 CAPD (M/F 17/12; mean age 34 +/- 10 years), and 29 healthy controls (M/F 17/12; mean age 32 +/- 8 years) were included. INTERVENTIONS: On ECG, minimum (QTmin) and maximum (QTmax) QT duration and their difference (QTd) were measured. In SA-ECG, duration of filtered QRS, HFLA signals less than 40 microV, and RMS voltage (40 ms) were also measured. RESULTS: Higher serum Ca2+ and lower K+ levels were found in CAPD compared to HD. All QT parameters were increased in HD and CAPD compared to controls. QT dispersion was significantly prolonged in HD compared to CAPD. In HD, QTd was correlated with left ventricular (LV) mass index (r = 0.53, p = 0.004), but not in CAPD (r = -0.09, p = 0.63). QT dispersion was significantly prolonged in patients with LV hypertrophy compared to patients without hypertrophy on HD (68 +/- 18 ms vs 49 +/- 18 ms, p = 0.008). In the analysis of SA-ECG, 3 of the 28 (11%) HD and 2 of the 29 (7%) CAPD patients had abnormal late potentials. Patients on HD and CAPD had significantly higher filtered-QRS duration compared to controls (105 +/- 15 ms and 104 +/- 12 ms vs 95 +/- 5 ms, respectively, p = 0.04). Patients with LV hypertrophy had higher filtered-QRS duration compared to patients without hypertrophy (109 +/- 12 ms vs 95 +/- 8 ms, p < 0.001). CONCLUSION: Dialysis patients had prolonged QTd and increased filtered-QRS duration in SA-ECG compared to controls. Patients on HD had longer QTd than patients on CAPD. QTd has been correlated to LV mass index in HD, but not in CAPD. This difference might be due to the effect of different dialysis modalities on electrolytes, especially the higher serum Ca2+ levels.     

Short-term effects of low-calcium dialysis solutions on calcium mass transfer, ionized calcium, and parathyroid hormone in CAPD patients.

Patients on CAPD using calcium carbonate (CaCO3) as phosphate binder might benefit from low-calcium (Ca) concentration dialysis solutions; however, no data are available for the effects of this regimen on Ca metabolism. We studied 10 patients on stable CAPD regimens with standard dialysis solutions (Ca 7 mg/dL) who were taking CaCO3 to control hyperphosphatemia (mean daily doses 4.5 +/- 2.4 g). Hypercalcemic episodes had been recorded in 6 patients. Standard dialysis solutions were replaced with solutions containing 5 mg/dL of Ca. Calcium and phosphate peritoneal mass transfer (MT), serum concentrations of total Ca, ionized Ca (Ca++), phosphate, intact PTH, and mid-molecular PTH, were evaluated before and 48 hours after change of dialysate. The switch to low-Ca solutions was accompanied by significant changes in calcium mass transfer (Ca MT) (+9.84 +/- 48.22 versus -96.74 +/- 48.32 mg/day, p less than .001). Ca MT was significantly (p less than .05) correlated with the serum/dialysate Ca gradient. There was no difference in phosphate MT. Serum Ca++ significantly (p less than .05) decreased from 5.20 +/- 0.32 to 4.88 +/- 0.36 mg/dL, and intact PTH significantly increased (81.5 +/- 139 versus 112.4 +/- 168 pg/mL, p less than .05). It is concluded that dialysis solutions with Ca 5 mg/dL result in a negative peritoneal Ca MT and can be useful to prevent and treat hypercalcemia in CAPD patients taking CaCO3 as phosphate binder. A careful monitoring of ionized calcium, PTH, and phosphate is suggested when an extensive and long-term use of this solution is considered.     

Cardiovascular risk factors in hemodialysis and peritoneal dialysis patients

BACKGROUND. Cardiovascular disease (CVD) is the major cause of mortality and morbidity of hemodialysis (HD) and peritoneal dialysis (CAPD) patients. We aimed to investigate the cardiovascular risk factors and their correlation with CVD in groups of HD and CAPD patients. METHODS. Thirty HD patients, 30 CAPD patients and 30 healthy controls were included in the study. Apolipoprotein A-l (apo A-l), apolipoprotein B (apo B), apolipoprotein(a) [Lp(a)] and high-sensitivity CRP (hs-CRP) were measured with a Beckman Coulter nephelometer, and homocysteine (Hcy) was determined with an Agilent HPLC analyzer. Lipid profile was determined with a Synchron LX 20 Pro analyzer. RESULTS. Hcy levels were 41.9+/-19.4, 41.8+/-38.5 and 9.3+/-3.5 micromol/L; Lp(a) levels were 325+/-315, 431+/-367 and 130+/-97 mg/L; hs-CRP levels were 3.78+/-3.21, 4.34+/-3.39 and 2.07+/-1.67 mg/L; apo A1/apo B ratios were 1.46+/-0.6, 1.36+/-0.5 and 1.80+/-0.59; total cholesterol levels were 3.56+/-0.7, 4.84+/-1.1 and 4.39+/-0.5 mmol/L; triglycerides were 1.44+/-0.5, 1.60+/-0.8 and 0.85+/-0.5 mmol/L in the HD, CAPD and control groups, respectively. CONCLUSION. HD and CAPD patients had higher Hcy, hs-CRP and Lp(a) levels and lower apo A/B ratios than controls. There was no significant difference between the HD and CAPD groups. Hypertension, age and hs-CRP showed a positive correlation with CVD.     

High-performance liquid chromatographic characterization of neurophysins in chronic renal failure

Levels of immunoreactive (IR) oxytocin (OT)-associated or estrogen-stimulated neurophysin (ESN) and vasopressin-associated or nicotine-stimulated neurophysin (NSN) were measured in plasma of patients with chronic renal failure before and after hemodialysis (HD) and intermittent peritoneal dialysis (IPD), and during continuous ambulatory peritoneal dialysis (CAPD). ESN-IR in 17 patients before HD was 24.4 +/- 2.7 ng/ml (mean +/- SEM) and increased after HD to 33.2 +/- 4.1 ng/ml (P less than 0.001). ESN-IR in 17 patients with CAPD was 15.2 +/- 3.4 ng/ml, significantly lower than in patients undergoing HD, P less than 0.001. In patients receiving IPD (n = 6), ESN was 11.6 +/- 3.7 ng/ml and did not change significantly after IPD. Levels of ESN in patients with renal failure were increased compared with levels in normal individuals, 1.0 +/- 0.1 ng/ml. Levels of ESN were not correlated with laboratory parameters that may be abnormal in renal failure. NSN levels in 16 of 17 patients undergoing HD were 3.2 +/- 0.34 ng/ml and in 14 of 17 patients with CAPD were 2.9 +/- 0.4 ng/ml, respectively. ESN before HD (r = 0.63, P less than 0.01), after HD (r = 0.85, P less than 0.001), and in patients with CAPD (r = 0.83, P less than 0.001) and IPD (r = 0.81, P less than 0.05) correlated significantly with an OT-like peptide previously found to be increased in renal failure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vitamin D and vitamin-D-binding protein kinetics in patients treated with continuous ambulatory peritoneal dialysis (CAPD)

Serum and dialysate levels of 25-hydroxycholecalciferol (25-OHD3), 1,25 dihydroxycholecalciferol (1,25-(OH)2D3), and vitamin-D-binding protein (DBP) were measured in 14 patients undergoing continuous ambulatory peritoneal dialysis (CAPD). Serum levels of 25-OHD3 and DBP were within normal range (29.1 +/- 22.9 nmol/L and 5.9 +/- 1.1 mumol/L, respectively). Serum levels of 1,25-(OH)2D3 were subnormal in all (less than 16 pmol/L) but one. In 5 patients, dialysate concentrations of 25-OHD3 were 2.3 +/- 0.9 nmol/L, the rest had levels less than 1.0 nmol/L. Small quantities of 1,25-(OH)2D3 were found in the dialysate effluents. DBP could be detected in the dialysate in all patients (0.24 +/- 0.06 mumol/L). Mass transfer (MT) of 25-OHD3 and DBP were respectively -10.4 +/- 8.3 nmol/24 h and -1.46 +/- 0.46 0.46 mumol/24 h. Peritoneal clearances of 25-OHD3 and DBP were low (0.40 +/- 0.37 mL/min and 0.18 +/- 0.06 mL/min, respectively. We conclude that CAPD leads to losses of 25-OHD3 and DBP. However, the peritoneal loss of DBP is well compensated and does not result in serum deficiency. Serum 25-OHD3 levels did not correlate with time on CAPD.     

Serum magnesium concentration is an independent predictor of parathyroid hormone levels in peritoneal dialysis patients.

BACKGROUND: Parathyroid hormone (PTH) is a cardinal factor in the pathogenesis of bone disease in the dialysis population. The spectrum of renal osteodystrophy has been reported to have changed during the past years, and adynamic bone disease has emerged as the most common bone disorder in these patients. Continuous ambulatory peritoneal dialysis (CAPD) is considered a risk factor for the development of this condition, and furthermore, the adynamic bone lesion is associated with a state of relative hypoparathyroidism (hypo-PTH). Calcium, vitamin D, and phosphorus play a key role in the control of parathyroid gland function in uremic patients. However, magnesium may also be able to modulate PTH secretion in a way similar to calcium. OBJECTIVE: The aims of this study were (1) to analyze the serum Mg concentration in a large group of CAPD patients, (2) to study the relationship between serum Mg and PTH levels, and (3) to investigate whether this relationship is independent of other factors, such as calcium, phosphorus, and calcitriol, that regulate parathyroid function. PATIENTS AND METHODS: We studied 51 stable patients, aged 23-77 years, under maintenance CAPD for more than 6 months (range 8-48 months). Calcium carbonate was used as a phosphate binder in all patients, and 9 subjects also received aluminum hydroxide. No patient had been previously treated with vitamin D. Biochemical parameters were prospectively evaluated over 6 months, and the mean values were computed. RESULTS: The mean serum Mg was 1.08 +/- 0.19 mmol/L, and hypermagnesemia, defined as a Mg level higher than 1.01 mmol/L, was found in 30 patients (59%). Thirty-one subjects (60%) had an intact PTH (iPTH) level lower than 120 pg/mL and were diagnosed as having relative hypo-PTH. Except for the values of iPTH and alkaline phosphatase, the only difference between the two groups was the serum Mg concentration, which was significantly higher in patients with hypo-PTH (1.16 +/- 0.15 mmol/L vs 0.91 +/- 0.14 mmol/L; p< 0.001). Furthermore, iPTH levels were lower in patients with hypermagnesemia than in subjects with normal serum Mg (69 +/- 49 pg/mL vs 190 +/- 89 pg/mL, p < 0.001). There was a significant correlation between serum Mg and PTH levels (r= -0.70, p< 0.01). After controlling for the effect of other variables by partial correlation analysis, a significant positive association between P and PTH (r= 0.25, p < 0.05), and a negative relationship between Mg and PTH (r= -0.57, p < 0.001) were evident. A forward stepwise multiple regression analysis showed that only P and Mg predicted PTH values (multiple r = 0.59, p < 0.001). CONCLUSIONS: Hypermagnesemia and hypoparathyroidism are frequent in CAPD patients. There is a significant inverse relationship between serum Mg concentration and iPTH levels. Furthermore, this association is independent of the most important factors regulating parathyroid gland function (calcium, phosphorus, and calcitriol). These results suggest that hypermagnesemia may have a suppressive effect on PTH synthesis and/or secretion. Therefore, elevated serum Mg levels may play a role in the pathogenesis of adynamic bone disease.     

Erythrocyte glutathione peroxidase activity,plasma malondialdehyde and erythrocyte glutathione levels in hemodialysis and CAPD patients

OBJECTIVES: Cardiovascular disease is the major cause of mortality in patients receiving hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) due to chronic renal failure. Increased lipid peroxidation and depletion of antioxidants may contribute to increased risk of atherosclerosis. We have therefore assessed the effect of hemodialysis and CAPD on oxidant and antioxidant status. DESIGN AND METHODS: Plasma malondialdehyde (MDA), Glutathione (GSH) levels and glutathione peroxidase (Gpx) activities were determined in 20 healthy persons (control), 20 patients on HD, 16 patients on CAPD. RESULTS: MDA was elevated in posthemodialysis and CAPD patients in comparison to prehemodialysis and control groups (posthemodialysis 1.39 +/- 0.38 nmol/mL, CAPD 1.26 +/- 0.27 nmol/mL, prehemodilaysis 0.83 +/- 0.22 nmol/mL, controls 0.72 +/- 0.21 nmol/mL p < 0.0001). With respect to antioxidants, glutathione levels were significantly lower in prehemodialysis, posthemodialysis and CAPD groups than those in control group (prehemodialysis 16.82 +/- 6.73 mg/dL RBC, posthemodialysis 31.43 +/- 11.88 mg/dL RBC, CAPD 40 +/- 12.72 mg/dL RBC, controls 62.26 +/- 24.01 mg/dL RBC, p < 0.0001). While erythrocyte GSH levels were significantly lower in the prehemodialysis patients than those in posthemodialysis and CAPD patients (p < 0.0001), it was significantly lower in posthemodialysis patients than those in CAPD patients (p < 0.05). There were no significant differences with respect to erythrocyte Gpx levels among the groups (p > 0.05). CONCLUSIONS: These findings indicate oxidative stress in patients with chronic renal failure which is further exacerbated by hemodialysis and CAPD, as evidenced by increased lipid peroxidation and low antioxidant levels.     

Red blood cell calcium level in chronic renal failure: effect of continuous ambulatory peritoneal dialysis

Red blood cell (RBC) calcium, calcium 45 influx, and calcium extrusion as indicated by Ca-stimulated, Mg-dependent adenosine triphosphatase (CaATPase) was determined in patients with chronic renal failure (CRF), patients with CRF receiving continuous ambulatory peritoneal dialysis (CAPD) treatment, and controls. Cell calcium, which in the controls was 5.5 mumol/L of cells, was elevated in patients with CRF--30.6 +/- 6.8 mumol/L of cells (p less than 0.002)--and in patients receiving CAPD-23.6 +/- 6.7 mumol/L of cells (p less than 0.02). Basal CaATPase activity in controls was 850.7 +/- 66.7 nmol inorganic phosphate per milligram of protein per hour. It was suppressed in patients with CRF and patients receiving CAPD: 504.9 +/- 34.4 nmol inorganic phosphate per milligram of protein per hour and 618.2 +/- 47.3 nmol inorganic phosphate per milligram of protein per hour, respectively (p less than 0.01). Calmodulin-stimulated CaATPase revealed a pattern similar to that of CaATPase basal activity. RBC calcium showed an inverse correlation with CaATPase activity (r = -0.935, p less than 0.005) in patients with CRF. Calcium influx was increased in patients with CRF and in patients receiving CAPD: 12.00 +/- 1.34 mumol/L of cells per hour and 13.60 +/- 1.70, respectively, compared with 4.61 +/- 0.39 mumol/L of cells per hour in controls (p less than 0.001). Patients with CRF have elevated RBC calcium levels mainly related to decreased extrusion and to increased influx. CAPD fails to improve substantially these abnormalities. Plasma vanadium levels were markedly elevated in patients undergoing hemodialysis and marginally in patients receiving CAPD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Blood pressure control and left ventricular hypertrophy in long-term CAPD and hemodialysis patients: a cross-sectional study.

BACKGROUND: It is still not clear whether hypertension and left ventricular hypertrophy (LVH) are more common in continuous ambulatory peritoneal dialysis (CAPD) than in hemodialysis (HD) patients. METHODS: To examine this subject, the indices of cardiac performance were compared between 50 HD and 34 CAPD patients. Patients were further divided into two subgroups [long-term (L) CAPD and L-HD] according to dialysis modality and duration of dialysis (more than 60 months' duration). RESULTS: The blood pressure and cardiothoracic index of CAPD patients did not differ from HD patients. On average, the left atrial index was 2 mm/m2 higher in HD patients than in CAPD patients. Left ventricular chamber sizes, wall thickness, and left ventricular mass index (LVMI) in patients on CAPD were similar to those of HD patients. Isovolumic relaxation time (IVRT) of CAPD patients was insignificantly less than that of HD patients (101 +/- 22 and 115 +/- 27 msec respectively). There was no significant difference between the two subgroups (L-HD and L-CAPD) in blood pressure, left atrial diameter, left ventricular chamber size, wall thickness, LVMI, ejection fraction, or IVRT. CONCLUSION: If normovolemia and normotension are obtained by strict volume control without using antihypertensive drugs, the effects of the two modalities of chronic dialysis treatment (HD and CAPD) on cardiac structure and function are not different from each other.     

Peritoneal accumulation of AGE and peritoneal membrane permeability.

BACKGROUND: In continuous ambulatory peritoneal dialysis (CAPD), the peritoneal membrane is continuously exposed to high-glucose-containing dialysis solutions. Abnormally high glucose concentration in the peritoneal cavity may enhance advanced glycosylation end-product (AGE) formation and accumulation in the peritoneum. Increased AGE accumulation in the peritoneum, decreased ultrafiltration volume, and increased peritoneal permeability in long-term dialysis patients have been reported. AIM: The purpose of the study was to evaluate the relation between peritoneal membrane permeability and peritoneal accumulation of AGE. METHODS: Peritoneal membrane permeability was evaluated by peritoneal equilibration test (PET) using dialysis solutions containing 4.25% glucose. Serum, dialysate, and peritoneal tissue levels of AGE were measured by ELISA method using polyclonal anti-AGE antibody. Peritoneal biopsy was performed during peritoneal catheter insertion [new group (group N), n = 18] and removal [long-term group (group LT), n = 10]. Peritoneal catheters were removed due to exit-site infection not extended into the internal cuff (n = 6) and ultrafiltration failure (n = 4) after 51.6+/-31.5 months (13 - 101 months) of dialysis. PET data obtained within 3 months after the initiation of CAPD or before catheter removal were included in this study. Ten patients in group N and 4 patients in group LT were diabetic. Patients in group LT were significantly younger (46.5+/-11.1 years vs 57.5+/-1.3 years) and experienced more episodes of peritonitis (3.5+/-2.1 vs 0.2+/-0.7) than group N. RESULTS: Peritoneal tissue AGE level in group LT was significantly higher than in group N, in both nondiabetic (0.187+/-0.108 U/mg vs 0.093+/-0.08 U/mg of hydroxyproline, p < 0.03) and diabetic patients (0.384+/-0.035 U/mg vs 0.152+/-0.082 U/mg of hydroxyproline, p < 0.03), while serum and dialysate levels did not differ between the groups in both nondiabetic and diabetic patients. Drain volume (2600+/-237 mL vs 2766+/-222 mL, p = 0.07) and D4/D0 glucose (0.229+/-0.066 vs 0.298+/-0.081, p < 0.009) were lower, and D4/P4 creatinine (0.807+/-0.100 vs 0.653+/-0.144, p< 0.0001) and D1/P1 sodium (0.886+/-0.040 vs 0.822+/-0.032, p < 0.0003) were significantly higher in group LT than in group N. On linear regression analysis, AGE level in the peritoneum was directly correlated with duration of CAPD (r = 0.476, p = 0.012), number of peritonitis episodes (r = 0.433, p = 0.0215), D4/P4 creatinine (r = 0.546, p < 0.027), and D1/P1 sodium (r = 0.422, p = 0.0254), and inversely correlated with drain volume (r = 0.432, p = 0.022) and D4/D0 glucose (r = 0.552, p < 0.0023). AGE level in the peritoneal tissue and dialysate were significantly higher in diabetics than in nondiabetics in group LT, while these differences were not found in group N. Serum AGE level did not differ between nondiabetics and diabetics in either group N or group LT. Drain volume and D4/D0 glucose were lower and D4/P4 creatinine and D1/P1 sodium higher in diabetics than in nondiabetics in both groups. CONCLUSION: Peritoneal accumulation of AGE increased with time on CAPD and number of peritonitis episodes, and was directly related with peritoneal permeability. Peritoneal AGE accumulation and peritoneal permeability in diabetic patients were higher than in nondiabetic patients from the beginning of CAPD.     

Continuous ambulatory peritoneal dialysis is responsible for an increase in plasma norepinephrine.

OBJECTIVE: To investigate the reason for increasing norepinephrine (NE) levels reported in continuous ambulatory peritoneal dialysis (CAPD) patients. METHODS: Norepinephrine was measured in the plasma and peritoneal dialysate of CAPD patients (n = 22) and in the plasma and the urine of healthy subjects (n = 20). It was also measured in the plasma of patients with chronic renal failure (CRF) (n = 15) and patients on hemodialysis (HD) (n = 15). RESULTS: It was found that NE was increased in CAPD patients compared with healthy individuals (687+/-221 pg/mL vs 199+/-25 pg/mL, p < 0.01).The daily removal of NE from the peritoneum of CAPD patients was lower compared with the amount of NE excreted in the urine of healthy subjects. Plasma NE increased after infusion of peritoneal dialysate. In 15 new patients on CAPD, it was found that NE plasma levels increased from 329+/-67 pg/mL before initiation of dialysis, to 584+/-173 pg/mL after 12 months of treatment (p < 0.01). Finally, plasma NE in CAPD patients (687+/-221 pg/mL) was significantly higher compared with the already increased levels in patients on HD or with CRF (406+/-143 pg/mL and 378+/-142 pg/mL, respectively). CONCLUSIONS: It is concluded that CAPD in patients with end-stage renal disease is responsible for a progressive increase of plasma norepinephrine.     

Normal or low initial PTH levels are not a predictor of morbidity/mortality in patients undergoing chronic peritoneal dialysis.

OBJECTIVE: During the past few decades, the pattern of bone disease in uremic patients has changed significantly. There has been an increase in the number of patients with normal or low initial parathyroid hormone (PTH) levels, particularly in patients on chronic peritoneal dialysis (CPD). Previous authors have described a higher prevalence of bone pain, microfractures, and fractures, and higher mortality among these patients. The aim of this study was to determine the incidence, morbidity, and mortality of patients who had a low or normal intact PTH (iPTH) level when they started CPD. DESIGN: We reviewed the records of 251 patients in our program that started CPD during the past 5 years (January 1996-December 2000). Clinical data, laboratory variables, medication, and dialysis parameters/dose were available at every clinic visit (approximately every 4 weeks). Intact PTH was used to express parathyroid function; values 3 times higher than the upper limit of normal (ULN) were assumed to be optimal. Variables predictive of the development of parathyroid dysfunction were calculated by univariate and multivariate logistic regression analysis. RESULTS: Of the patients who started CPD, 15.5% had iPTH values below the ULN (7.6 pmol/L), and an additional 29.5% had an iPTH of less than 3 times the ULN (i.e., between 7.6 and 22.8 pmol/L). We call these two groups of patients the normal/low initial iPTH group. During the follow-up period (3-63 months), we found a trend toward increasing iPTH levels. By the end of the study period, 61.2% of those with normal/low initial iPTH remained in the normal/low iPTH range, and 38.8% had converted to a group with an iPTH range higher than 22.8 pmol/L. The patients who converted their iPTH grouping were younger, fewer of them were diabetics (p = not significant), and they were more frequently on low calcium dialysate (p < 0.05). Hyperphosphatemia was an independent risk factor for subsequent iPTH changes during the course of continuous ambulatory PD treatment. All patients in the normal/low iPTH groups had a low prevalence of bone fractures (3.5%). Also, patients who remained in the normal/low iPTH group at the end of the follow-up period did not have more fractures than those who converted to the hyperparathyroid group (3.8% vs 3.1%). We found no differences in bone fractures between patients with iPTH levels below 22.8 and those with levels above 22.8 pmol/L (3.5% vs 5.4%), nor were there differences in patient and technique survival between these two groups. CONCLUSION: Normal/low initial iPTH is a frequent finding among patients starting CPD. Serum phosphorus was an independent risk factor for subsequent iPTH changes during the course of CPD treatment. Use of low calcium dialysate was significantly higher in patients who converted their iPTH into the high iPTH range. Very few patients with low/normal iPTH had bone-related symptoms (pain and fractures), and their morbidity and mortality did not differ from those patients with a high initial iPTH level.     

Characterization of subtypes of hypertension in CAPD patients by cyclic guanosine monophosphate.

OBJECTIVE: While most hypertensive patients with end-stage renal disease normalize high blood pressure with fluid removal by continuous ambulatory peritoneal dialysis (CAPD), there is a significant proportion of CAPD patients whose blood pressure can be controlled only by antihypertensive drugs. METHOD AND PATIENTS: To study the hypothesis that such patients are still volume overloaded, we used plasma cyclic guanosine monophosphate (cGMP) as a marker for hydration status. Thirty-two CAPD patients were divided into 3 groups: group 1, normotensive patients (n = 12); group 2, hypertensive patients who normalized their blood pressure with fluid removal (n = 12); group 3, hypertensive patients whose blood pressure was refractory to intensified fluid removal (n = 8). RESULTS: Mean cGMP levels were significantly higher in dialysis-sensitive hypertension (27 +/- 5 pmol/mL) than in dialysis-refractory hypertension (15 +/- 2 pmol/mL), or in normotensive patients (13 +/- 4 pmol/mL). Reduction of excess fluid in volume overloaded hypertensive CAPD patients resulted in a normalization of cGMP levels (14 +/- 8 pmol/mL), but did not affect this volume marker in patients with dialysis-resistant hypertension (10 +/- 4 pmol/mL). CONCLUSION: Plasma cGMP levels are elevated in volume overload-induced hypertension complicating CAPD. Hypertensive CAPD patients whose plasma cGMP levels are within normal limits have raised blood pressure refractory to volume removal. Our findings are consistent with the hypothesis that inadequate removal of excess volume plays a major role in a subset of patients with CAPD hypertension.     

Transport kinetics of pseudouridine during hemodialysis and continuous ambulatory peritoneal dialysis

It has been found that the concentrations of pseudouridine in serum of patients undergoing continuous ambulatory peritoneal dialysis (CAPD) are higher than those in patients undergoing hemodialysis. We analyzed whether this could be caused by a lower rate of transport in CAPD when compared with hemodialysis. Mass transfer area coefficients (MTCs) for urea, creatinine, uric acid, and pseudouridine were determined in nine patients undergoing hemodialysis as dialyzer clearances and in 14 patients undergoing CAPD during a 4-hour dwell with 2 L dialysate with glucose, 70 mmol/L. The theoretical MTC of pseudouridine (TPSI), calculated by extrapolation to its molecular weight by use of the MTC of urea, creatinine, and uric acid, was higher than the observed MTC of pseudouridine, both in hemodialysis (136 vs 112 ml/min, p less than 0.025) and in CAPD (6.9 vs 3.4 ml/min, p less than 0.001). The pseudouridine/TPSI MTC ratio was lower during CAPD than during hemodialysis (0.47 vs 0.83, p less than 0.0005), indicating a lower level of transport during CAPD. In vitro experiments with nuclear magnetic resonance spectroscopy supported the hypothesis of glucose-induced molecular association of pseudouridine. Therefore, dialysate containing 10 mmol/L glucose was compared with that containing 70 mmol/L glucose in eight patients undergoing CAPD. The MTC of pseudouridine was higher during the experiments with dialysate containing 10 mmol/L glucose (3.5 +/- 2.0 ml/min vs 2.7 +/- 1.9 ml/min, p less than 0.05). This was also found for the pseudouridine/TPSI MTC ratio (0.61 vs 0.41, p less than 0.02) and the pseudouridine/creatinine MTC ratio (0.33 vs 0.25, p less than 0.02), favoring glucose-induced decrease of MTC-pseudouridine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of hemostatic disturbances between patients on CAPD and patients on hemodialysis.

OBJECTIVE: Disturbances in hemostasis are common findings in uremic patients. Both bleeding diathesis and thrombosis are observed. The purpose of this study was to assess whether renal replacement therapy in the form of hemodialysis (HD) or continuous ambulatory peritoneal dialysis (CAPD) affects coagulation and fibrinolysis in patients with end-stage renal failure. DESIGN: Comparison of hemostatic measures in patients on CAPD, HD, and matched healthy controls. SETTING: Department of Nephrology and Internal Medicine, Bialystok University School of Medicine. PATIENTS AND METHODS: Twenty-four HD patients and 23 CAPD patients were evaluated with respect to platelet aggregation, hemostatic parameters, serum lipids, lipoprotein(a), and cytokines [tumor necrosis factor alpha (TNFalpha) and interleukin-1 (IL-1)]. INTERVENTIONS: Four exchanges of CAPD per day, using 2.0 L dialysate over a period of 25 +/- 31 months; or 4-5 hours of HD 3 times per week for a period of 31 +/- 22 months. RESULTS: Platelet aggregation in whole blood and platelet-rich plasma was significantly impaired in both groups of dialyzed patients compared to healthy volunteers. Markers of endothelial cell injury (thrombomodulin and von Willebrand factor) were significantly higher in HD and CAPD patients compared to the control group. A similar pattern of changes was observed for lipoprotein(a), fibrinogen, tissue factor pathway activity, and factor VII activity. Activity of factor X was significantly enhanced in CAPD compared to HD patients and controls. Euglobulin clot lysis time was significantly prolonged in HD and CAPD patients over controls, being more prolonged in CAPD patients. Markers of ongoing coagulation (thrombin-antithrombin complexes and prothrombin fragments 1+2) were higher in uremic patients, significantly higher in CAPD than in HD. A marker of ongoing fibrinolysis (plasmin-antiplasmin complexes) was higher in uremic patients but was lower in CAPD than in HD patients. Concentrations of TNFalpha and IL-1 were higher in HD than in CAPD patients. CONCLUSION: Patients on CAPD showed evidence of a higher degree of hypercoagulation than HD patients.Thus, hemostatic abnormalities in end-stage renal failure may be affected to some extent by the choice of renal replacement therapy.     

Can the inflammation markers of patients with high peritoneal permeability on continuous ambulatory peritoneal dialysis be reduced on nocturnal intermittent peritoneal dialysis?

BACKGROUND: Patients with high peritoneal permeability have the greatest degree of inflammation on continuous ambulatory peritoneal dialysis (CAPD), which may be associated with their higher mortality. Nocturnal intermittent peritoneal dialysis (NIPD; "dry day") may decrease inflammation by reducing the contact between dialysate and peritoneum and/or providing better fluid overload control. Therefore, the aims of this study were to determine and compare serum and dialysate concentrations of C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor alpha (TNF-alpha) of patients with high or high-average peritoneal transport on CAPD, changed to NIPD, and ultimately to continuous cyclic peritoneal dialysis (CCPD). METHODS: Crossover clinical trial in 11 randomly selected patients. All subjects had been on CAPD and were changed to NIPD, and ultimately to CCPD (6.4 +/- 3.1 months after initiation of study). All patients used glucose-based dialysate. Evaluations of clinical and biochemical parameters, dialysis adequacy, and serum and dialysis inflammation markers were performed at baseline on CAPD, 7 - 14 days after changing to NIPD, 7 - 14 days after switching to CCPD, and after 1 year of follow-up. All patients used only 1.5% glucose dialysate during evaluation days. CRP was determined by nephelometry, and IL-6 and TNF-alpha by ELISA. RESULTS: Seven patients were high transporters and 4 high average. Ultrafiltration increased (p < 0.05) when patients changed from CAPD [0.38 L (-0.3 - 1.1 L)] to NIPD [2.64 L (0.7 - 4.7 L)]; it then decreased on CCPD [0.88 L (0.4 - 1.3 L) and at the end of study [0.65 L (0.3 - 1.0 L)]. This better fluid overload control was accompanied by decreased weight and systolic and diastolic blood pressure when patients changed from CAPD (89 +/- 13 kg, 160 +/- 23 and 97 +/-9 mmHg, respectively) to NIPD (86 +/- 17 kg, 145 +/- 14 and 86 +/- 9 mmHg, respectively), and increased weight and systolic and diastolic blood pressure on CCPD (85 +/- 15 kg, 143 +/-23 and 88 +/- 14 mmHg, respectively) and at the end of follow-up (87 +/- 16 kg, 155 +/- 24 and 89 +/- 12 mmHg, respectively). Median serum CRP decreased (p = 0.03), from 3.8 (1.6 - 8.5) mg/L on CAPD to 1.0 (0.4 - 4.4) mg/L on NIPD, but increased on CCPD [1.8 (1.3 - 21) mg/L] and at the end of the study [3.2 (0.3 - 8.2) mg/L]. Dialysate CRP decreased nonsignificantly, from 0.10 (0 - 0.5) mg/L on CAPD to 0 (0 - 0.03) mg/L on NIPD, to 0.01 (0 - 0.08) mg/L on CCPD, and to 0 (0 - 0) mg/L at final evaluation. Serum TNF-alpha concentration decreased, from 0.14 (0.04 - 0.6) pg/mL on CAPD to 0.01 (0 - 0.08) pg/mL on NIPD, and then increased to 0.06 (0 - 0.4) pg/mL on CCPD and to 0.11 (0 - 0.2) pg/mL at the end of the study; whereas dialysate TNF-alpha decreased, from 0.08 (0.03 - 0.2) pg/mL on CAPD to 0.04 (0 - 0.2) pg/mL on NIPD, and to 0 (0 - 0) pg/mL and 0 (0 - 0.05) pg/mL on CCPD and final evaluation respectively. Serum IL-6 decreased (p = 0.07), from 2.5 (2.0 - 4.2) pg/mL on CAPD to 1.0 (0.7 - 2.0) pg/mL on NIPD, and to 1.0 (0.8 - 2.9) pg/mL on CCPD and 1.0 (0.5 - 9.8) pg/mL at the end of the study; whereas dialysate levels remained similar on CAPD [8.0 (3.7 - 13) pg/mL] and NIPD [7.8 (5.1 - 23) pg/mL], and increased on CCPD [11.2 (9.5 - 19) pg/mL] and at final evaluation [11.2 (8.3 - 15) pg/mL]. CONCLUSIONS: NIPD significantly decreased serum CRP and displayed a trend to decrease TNF-alpha and IL-6 serum concentrations compared with CAPD; whereas CCPD tended to reverse these effects. These results did not appear to be due to decreased local peritoneal inflammation, but they could be associated with better control of fluid overload on NIPD. Thus, NIPD, as Long as the residual renal function allows it, may be useful in reducing the systemic inflammation of patients with high peritoneal membrane permeability.     

Positive correlation of serum bio-intact PTH(1-84) but not intact PTH with parathyroid gland size in hemodialysis patients.

To evaluate the usefulness of newly-developed bio-intact parathyroid hormone (Bio-PTH) assay, which measures exclusively intact PTH(1-84) molecule, serum PTH level determined by Bio-PTH assay, in comparison with second-generation intact PTH (I-PTH) assay, was examined for its correlation with parathyroid gland size. Serum PTH was determined in 46 male HD patients, together with bone formation markers bone alkaline phosphatase, intact osteocalcin, N-terminal propeptide of type I collagen, and bone resorption markers deoxypyridinoline, pyridinoline, beta-crossLaps. Maximal diameter of parathyroid gland was determined with ultrasonography as the parathyroid gland size. Serum Ca and Pi correlated significantly with parathyroid gland size rationalizing our method to define parathyroid gland size. Serum Bio-PTH was correlated significantly in a positive manner with parathyroid gland size (R = 0.308, P = 0.0474), whereas serum I-PTH did not. Furthermore, parathyroid gland size did not exhibit a significant correlation with any of bone formation markers or bone resorption markers. The lack of correlation between bone markers and parathyroid gland size in HD patients may be explained by the occurrence of refractoriness of bone to PTH. In conclusion, serum Bio-PTH assay could provide a better assay than I-PTH assay to estimate parathyroid function in HD patients, due mainly to its exclusive correlation with parathyroid gland size.     

The influence of dialytic modality on arterial stiffness, pulse wave reflections, and vasomotor function.

BACKGROUND: Measurements of aortic stiffness [aortic pulse wave velocity (PWV) and augmentation index (Alx)] have been established as powerful predictors of survival on hemodialysis (HD). Abnormal endothelial-dependent and endothelial-independent vascular reactivity and increased arterial stiffness are commonly described in HD patients. There is, however, a lack of information on the comparative impact of different renal replacement therapies (RRTs) on PWV and Alx, and how these different methods might influence endothelial-dependent abnormal vasodilatation. OBJECTIVE: To describe in a cross-sectional design arterial compliance and distensibility in continuous ambulatory peritoneal dialysis (CAPD) versus HD versus renal transplant (RTx) patients, compared with age- and blood pressure-matched essential hypertensive controls. The PWV and aortic Alx were determined from contour analysis of arterial waveforms recorded by applanation tonometry in 40 CAPD, 41 HD, 20 RTx patients (with normal serum creatinine), and 20 controls with essential hypertension (all normotensive under treatment). Endothelial-dependent and endothelial-independent vascular reactivities were assessed by changes in Alx following challenges with inhaled salbutamol and sublingual nitroglycerin respectively. RESULTS: CAPD patients had significantly stiffer arteries than all other categories. The PWV was 8.29 +/- 1.09 m/ second in CAPD patients, significantly higher (p < 0.05) compared to HD subjects (7.19 +/- 1.87 m/s). Both dialysis subgroups had significantly higher PWV values compared to RTx patients (6.59 +/- 1.62 m/s) and essential hypertensive controls (6.34 +/- 1.32 m/s), p < 0.05. The Alx had a profile similar to PWV in different RRTs. All groups with the exception of CAPD subjects had a significant decrease in Alx following salbutamol. Moreover, the vasodilatation induced by either nitroglycerin or salbutamol was significantly blunted compared to HD. Overall, both dialysis categories had more abnormal responses compared to RTx patients and essential hypertensive controls. CONCLUSION: CAPD is associated with stiffer arteries and more profoundly abnormal endothelial-dependent vasomotor function, compared to matched HD subjects. These differences in arterial physical properties might explain differences seen in cardiac structure and function between the RRTs.