Association of Hypertriglyceridemia and Insulin Resistance in UREMIC Patients Undergoing CAPD

Objective

Hyperlipidemia is frequently encountered in uremic patients and may be worsened by continuous ambulatory peritoneal dialysis (CAPD) treatment. The lipid abnormalities in these patients may be multifactorial. Insulin resistance (or its compensatory hyperinsulinemia) is commonly observed in uremic patients, but its association with hyperlipidemia in these patients has not been studied.

Patients and Methods

Lipid profiles of 35 nondiabetic nonobese patients undergoing CAPD for more than 1 year (mean 52.3 months) were studied. Current laboratory data and parameters related to peritoneal dialysis (PD) within the previous 3 months were recorded. After overnight fasting and interruption of PD, an oral 75-g glucose tolerance test (OGTT) was examined.

Results

After CAPD treatment for more than 12 months, these patients had higher serum triglyceride (TG) ( p = 0.001) and total cholesterol ( p = 0.0058) levels than their values before commencing CAPD. Twelve of 14 patients with serum TG higher than 200 mg/dL (high-TG) were diagnosed de novo, in contrast with only 1 patient diagnosed of de novo hypercholesterolemia (total cholesterol > 240 mg/dL). There was no difference in age, gender, body mass index (BMI), duration of PD treatment, serum albumin, hematocrit, intact serum parathyroid hormone (iPTH), peritoneal glucose load, solute transport, or weekly Kt/V urea between normal-TG and high-TG patients. After adjusting for age, gender, BMI, weekly Kt/V urea, and iPTH, the high-TG patients had higher levels of area under the curve for glucose (AUCGlu), area under the curve for insulin (AUCIns), and AUCIns/AUCGluratios (F = 10.63, 10.14, and 8.65; p = 0.0029, 0.0035, and 0.0065, respectively), indicating that the high-TG patients were more insulin resistant. There were 24 patients with normal glucose tolerance (NGT), and 11 patients with impaired glucose tolerance (IGT). The IGT group had higher serum TG (F = 10.43, p = 0.003) and total cholesterol (F = 8.05, p = 0.009) than the NGT group, after adjusting for BMI, duration of CAPD treatment, peritoneal glucose load, solute transport, serum albumin, and lipid levels before PD treatment. The TG levels after CAPD treatment were positively correlated with AUCGlu, AUCIns, and AUCIns/AUCGluratio ( r = 0.48, 0.53, and 0.49; p = 0.0037, 0.001, and 0.0028, respectively).

Conclusions

These results indicate that insulin resistance is an important factor in the development of hypertriglyceridemia in CAPD patients.

New-Onset Diabetes Mellitus in Peritoneal Dialysis and Hemodialysis Patients: Frequency, Risk Factors, and Prognosis-A Review

New-onset diabetes mellitus (NODM) is observed in both hemodialysis (HD) and peritoneal dialysis (PD) patients. The prevalence of NODM in dialysis patients is slightly higher compared to subjects of the general population. Based on currently published data there is no convincing evidence that the risk of NODM is different between HD and PD patients. Data on the effect of glucose load on risk of NODM in dialysis patients remain controversial. PD modality (automated or continuous ambulatory PD) has no significant influence on NODM incidence. Chronic inflammation is associated with NODM in dialysis patients. Reported differences in NODM between PD and HD patients are possibly also influenced by differences in demographic factors between these patient groups. Mortality in NODM patients is lower than mortality in patients with preexisting DM. This may be partly explained by the younger age and lower number of comorbidities in patients with NODM.

Serum Aluminum Levels and Peritoneal Dialysis

Serum aluminum levels, significantly higher in dialysis patients than in normal subjects, were also found to be significantly higher in patients on PD than in those on HD. This could be related to a higher Al transport rate across membrane during PD than during HD. The easier contamination of PD dialysates and their acidic pH could account for this trend to a positive Al balance in PD.

On the basis of our observations, however, the significance of the serum aluminum level could be very low, since aluminemia does not seem to reflect the cumulative amount of Al ingested and might not readily help predict the risk of Al intoxication.

Glucose tolerance in patients undergoing continuous ambulatory peritoneal dialysis

The effects of continuous ambulatory peritoneal dialysis (CAPD) on glucose tolerance and serum immunoreactive insulin and glucagon responses to oral glucose over the first year of therapy were studied in 13 uremic patients. Oral glucose tolerance tests were performed before treatment started, and again after 3 and 12 months on CAPD. Before CAPD, the patients showed decreased glucose tolerance. However, neither fasting blood glucose and serum insulin and glucagon levels nor the insulin and glucagon levels during the tests were significantly different from results obtained in 13 healthy controls. During CAPD, the mean intraperitoneal supply of glucose from the dialysates varied between 121 and 245 g/day and did not change during the study period. Glucose tolerance and hormone responses to glucose did not change during the study period. No patient developed manifest diabetes mellitus. We conclude that glucose intolerance in uremia persists during CAPD, but despite the continuous peritoneal absorption of 100-200 g of glucose during CAPD, the treatment had no effect on glucose tolerance and insulin secretory response.

New-Onset Hyperglycemia in Nondiabetic Chinese Patients Started on Peritoneal Dialysis

BACKGROUND

Glucose has been used as the osmotic agent added to standard peritoneal dialysis (PD) solutions since its inception. Patients who have no history of glucose intolerance may develop hyperglycemia after the initiation of PD therapy. However, the prevalence and long-term implications of new-onset hyperglycemia in PD patients has not been studied.

METHODS

We studied 405 consecutive patients with renal failure newly started on PD therapy. Fasting plasma glucose levels 1 month after being stable on PD therapy were reviewed. Clinical factors affecting fasting plasma glucose levels were explored. Patients were followed up for 49.7 +/- 28.4 months.

RESULTS

Of 405 patients, 136 had underlying diabetic nephropathy and another 17 had preexisting diabetes before starting PD therapy. Of the remaining 252 patients, fasting plasma glucose levels were greater than 200 mg/dL (>11.1 mmol/L) in 21 (8.3%) and 126 to 200 mg/dL (7.0 to 11.1 mmol/L) in 48 patients (19.0%). Seven patients required insulin therapy, 3 required low-dose sulfonylurea therapy, and all other patients had glucose levels controlled by means of dietary restriction only. Fasting plasma glucose levels significantly correlated with patient age (Pearson r = 0.278; P < 0.001), Charlson comorbidity score (r = 0.484; P < 0.001), baseline serum C-reactive protein level (r = 0.390; P < 0.001), and serum albumin level (r = -0.182; P < 0.001). However, patients with new-onset hyperglycemia had similar values for body weight, body mass index, peritoneal transport parameters, and ultrafiltration profile compared with other patients. At 36 months, actuarial survival rates were 93.7%, 85.3%, 81.6%, and 66.7% for patients with fasting glucose levels less than 100, 100 to less than 126, 126 to less than 200, and 200 mg/dL or greater (5.6, 5.6 to <7.0, 7.0 to <11.1, and >or=11.1 mmol/L) and 65.9% for patients with preexisting diabetes, respectively (overall log rank test, P < 0.001).

CONCLUSION

New-onset hyperglycemia is common in patients without diabetes started on PD therapy. Contrary to common belief, obese patients do not appear to have a greater risk of hyperglycemia. Our results suggest that even mild hyperglycemia, with fasting plasma glucose level greater than 100 mg/dL (>5.6 mmol/L), is associated with worse survival in PD patients.

Loss of zinc and selenium does not occur through peritoneal dialysis

A prospective study was done to determine whether zinc (Zn) and selenium (Se) loss occurs in patients on continuous ambulatory peritoneal dialysis through their dialysate effluent. Fifty pairs of aliquots of dialysis fluid were collected from 29 patients. Each paired set of specimens consisted of the dialysate fluid before instillation into the peritoneal cavity and a specimen of the spent effluent after dialysis for comparison. Zn and Se concentrations were measured using inductively coupled plasma atomic emission spectrophotometry. The range of dialysate fluid Zn concentration before instillation was 0 to 1.75 microg/mL and that for Se was 0 to 0.33 microg/mL. Ranges for Zn and Se in the postdialysis effluent were 0 to 0.60 and 0 to 0.56 microg/mL, respectively. The concentration differences in 50 pairs of samples were analyzed with Wilcoxon's test. The difference in Zn levels between the predialysis specimen and the effluent was 0.009 +/- 0.036 microg/mL (P = 0.154). The difference for Se was 0.018 +/- 0.21 microg/mL (P = 0.118). In conclusion, no significant loss or gain of Zn or Se occurs in patients undergoing continuous ambulatory peritoneal dialysis.

Experimental use of raffinose as an osmotic agent for peritoneal dialysis

Conventional glucose-based solutions for peritoneal dialysis fluids have been shown to raise problems of biocompatibility. We therefore evaluated the ultrafiltration capabilities of raffinose as an alternative osmotic agent in a non-uremic rat model. Animals were divided into four groups and injected intraperitoneally with solutions containing raffinose (4.5%, 345 mOsm/kg; 16.7%, 518 mOsm/kg) or glucose (1.5%, 346 mOsm/kg; 4.25%, 489 mOsm/kg). Data obtained from animals exposed to 16.7% raffinose were excluded because of precipitation of the osmotic agent. Low-osmolality raffinose solution induced higher ultrafiltered volume than the low-osmolality glucose-enriched fluid at 120 minutes of dwelling time. No significant differences were observed in effluent sodium and potassium concentration and protein dialysate-to-plasma (D/P) ratio. The D/P ratio of phosphate was higher in the low-osmolality raffinose-based fluid than in the low-osmolality glucose solution. The osmolality of the solutions was significantly decreased after a dwelling time of 120 minutes. We conclude that 4.5% raffinose is an effective osmotic agent. Total or partial replacement of glucose by raffinose for clinical peritoneal dialysis could be eventually considered after appropriate evaluation of its biocompatibility and general side effects.

Trace elements in serum, packed cells, and dialysate of CAPD patients

Neutron Activation Analysis (NAA) was used to investigate trace element patterns in serum, packed cells, and dialysate of CAPD patients. The concentrations of the elements Cs, Cu, Fe, and Mn in serum and packed cells appeared to be maintained within the normal range, while the levels of the non-essential element Br in both serum and packed cells were subnormal. The serum Cr values were extremely high (20 to 50 times higher than the normal serum level). The amount of Cr absorbed from the dialysate was calculated to be ten times higher than the daily dietary uptake. The Co concentrations were normal in packed cells but were significantly increased in serum. The Rb content in packed cells was slightly lower than normal, while the serum value was normal. Se was maintained within the normal range in packed cells, but the serum concentration was slightly lower than normal. The concentrations of Zn were low in serum and appeared to be higher than normal in packed cells. In conclusion, this analysis of the trace element status of CAPD patients reveals two major abnormalities. There is an apparent loss of Br from the blood towards the dialysate and on the other hand, a dramatic accumulation of Cr into the blood as a result of the very high Cr content in the dialysate.

Aluminum associated bone disease: clinico-pathologic correlation

A chemical, aurine tricarboxylic acid was used to identify aluminum in bone in a group of chronic renal failure patients with severe osteomalacia. Thirteen out of 49 (26%) patients had a positive stain at the bone-osteoid junction. The presence of aluminum at the staining site was confirmed by electron dispersion x-ray analysis. The patients' biopsies staining negative with this clinical, although having high bone aluminum levels, had more significant features of hyperparathyroidism, both biochemically and histologically than those having a positive stain. The usefulness of this technique to diagnose presymptomatic aluminum related osteomalacia is emphasized.

Biochemical studies on patients undergoing continuous ambulatory peritoneal dialysis

Biochemical studies are being performed in chronically renal insufficient patients undergoing treatment by CAPD. Serum protein and albumin levels have remained stable during treatment as have the ratios of essential/non-essential amino acids and valine/glycine in plasma. Dietary intake therefore appears to adequately compensate dialysate losses. Serum calcium and phosphate as well as immunoreactive parathyroid hormone concentration and alkaline phosphatase levels did not change during the treatment. The glucose load due to the high concentrations of glucose in the dialysate may have adverse effects on the glucose tolerance and insulin secretion of CAPD patients. However, in fasting patients it could be shown that only the 4.25% glucose dialysate causes any increase in plasma glucose levels with a concommitant rise of insulin secretion, an exchange with a 1.5% glucose dialysate having relatively little effect on these parameters. Quantification of the individual serum lipoproteins is also being performed during CAPD. No changes were observed in alpha-cholesterol levels, but 50% of the patients have shown significant increases in total serum cholesterol, beta-cholesterol and serum triglycerides in the course of treatment. In these cases dietary consequences must be considered in order to minimise the potential artherosclerotic risk.