Colonic transit time in long-term dialysis patients

Uremic toxins originating from colonic microbial metabolism

Numerous molecules, which are either excreted or metabolized by the kidney, accumulate in patients with chronic kidney disease (CKD). These uremic retention molecules (URMs), contributing to the syndrome of uremia, may be classified according to their site of origin, that is, endogenous metabolism, microbial metabolism, or exogenous intake. It is increasingly recognized that bacterial metabolites, such as phenols, indoles, and amines, may contribute to uremic toxicity. In vitro studies have implicated bacterial URMs in CKD progression, cardiovascular disease, and bone and mineral disorders. Furthermore, several observational studies have demonstrated a link between serum levels of bacterial URMs and clinical outcomes. Bacterial metabolism may therefore be an important therapeutic target in CKD. There is evidence that besides reduced renal clearance, increased colonic generation and absorption explain the high levels of bacterial URMs in CKD. Factors promoting URM generation and absorption include an increased ratio of dietary protein to carbohydrate due to insufficient intake of fiber and/or reduced intestinal protein assimilation, as well as prolonged colonic transit time. Two main strategies exist to reduce bacterial URM levels: interventions that modulate intestinal bacterial growth (e.g., probiotics, prebiotics, dietary modification) and adsorbent therapies that bind bacterial URMs in the intestines to reduce their absorption (e.g., AST-120, sevelamer). The efficacy and clinical benefit of these strategies are currently an active area of interest.

Identification of hemodialysis patients' common problems using the International Classification of Functioning, Disability and Health

The aim of this study was to identify the common health problems of Japanese patients on hemodialysis (HD) using the International Classification of Functioning, Disability and Health (ICF). The participants of this study had been on HD for at least five years when they were interviewed. The ICF checklist was used to initially interview 32 HD patients. Fifty-seven categories of the ICF Checklist were identified as impaired; another 35 ICF categories, chosen based on interviews and expert discussion, as well as 8 categories relevant to HD, were included in the final checklist. This final checklist was then used to interview 104 patients. Overall, 10 categories in "Body functions" and 3 categories in "Body structures" were reported as problems by more than 50% of patients. Two categories in "Activities and participation" and 4 categories in "Environmental factors" were reported as restricted or a barrier for more than 30% of patients. A higher percentage of patients who started HD before 50 years of age and had a longer duration of HD reported problems in "Body functions" and "Body structures", while more patients with a shorter duration of HD reported problems in relationships with their family. Japanese patients on maintenance HD have various physical and psychosocial problems. In addition, HD duration and the age when HD was started affect patients' reports of physical and psychosocial problems.

Gastrointestinal symptoms in patients with end-stage renal disease undergoing treatment by hemodialysis or peritoneal dialysis

OBJECTIVES

The aim of this study was to determine the prevalence of gastrointestinal symptoms in patients with end-stage renal disease undergoing hemodialysis (HD) or peritoneal dialysis (PD) treatment.

METHODS

Patients undergoing HD or chronic ambulatory PD in the Department of Renal Medicine of our hospital were asked to complete a locally validated Rome II questionnaire. The same questionnaire was also administered to age- and gender-matched medical outpatients without renal failure, and community subjects. Patients on HD and their outpatient controls also completed the Hospital Anxiety and Depression Scale.

RESULTS

A total of 148 patients with end-stage renal disease (HD 100, PD 48) completed the study. Their results were compared with those of 148 age- and gender-matched medical outpatients without renal failure and 148 randomly selected community controls. Patients on dialysis treatment were more likely to have abdominal pain, use laxatives, and report symptoms consistent with functional vomiting and irritable bowel syndrome (IBS) (70%, 55%, 16%, and 25%) than age- and gender-matched medical outpatients without renal failure (21%, 11%, 1%, and 6%) and community controls (16%, 4%, 0%, and 8%). Among HD patients and their outpatient controls, the differences appeared to be unrelated to anxiety or depression.

CONCLUSIONS

Abdominal pain, laxative use, functional vomiting, and IBS were more common in uremic individuals than in controls without renal failure. Our data have not shown whether these differences are due to the uremic state itself, or, alternatively, its treatment.

Superior dialytic clearance of β2-microglobulin and p-cresol by high-flux hemodialysis as compared to peritoneal dialysis

Both residual renal and dialytic clearance confer to the total solute clearance in dialysis patients. Dialytic clearances of the middle molecule beta-microglobulin (beta(2)M) and the protein-bound solute p-cresol (pcr) are generally believed to be higher with peritoneal dialysis (PD) as compared to hemodialysis (HD). Supportive data, however, are lacking. We performed a single-center cross-sectional observational study including 70 unselected patients treated with either high-flux HD (n=20) or PD (n=50). Mid-day serum levels (PD) and time-averaged concentrations (HD) of the water-soluble solutes urea nitrogen, creatinine and phosphate, the middle molecule beta(2)M, and the protein-bound solute pcr were determined. Dialytic solute clearances (l/week/1.73 m(2)) were calculated from total dialysate collection during the mid-week session in HD and 24 h dialysate collection in PD. Renal clearances were calculated for each of the respective solutes from a timed urine collection. Total clearances were obtained by summation. HD delivered significantly higher clearances of all retention solutes studied. This superiority was especially pronounced for pcr (30.9+/-62.7 vs 4.4+/-2.3, HD vs PD, P<0.0001) and beta(2)M (28.6+/-6.6 vs 5.8+/-3.1, HD vs PD, P<0.0001). Renal clearances, conversely, were significantly higher in patients on PD. Serum levels of all solutes but pcr were significantly lower in HD than in PD. Both a higher residual renal function and a lower generation rate contribute to the lower pcr levels in PD. In conclusion, superior dialytic clearance of both water-soluble solutes, beta(2)M, and pcr is achieved by high-flux HD as compared to PD.