Serum cystatin C is a determinant of paraoxonase activity in hemodialyzed and renal transplanted patients.

BACKGROUND: Human paraoxonase-1 (PON1) inhibits LDL-oxidation and atherogenesis, and possesses lactonase activity. Decreased PON1 activity was found in hemodialyzed and renal transplanted patients. Cystatin C plays a protective role in atherosclerosis, and is a new, sensitive marker of renal function. The relationship between these two markers in renal failure has not been investigated. AIMS: The goal of this study was to clarify the relationship between PON1 activity, cystatin C and homocysteine in chronic renal failure. We also determined the levels of oxidatively modified LDL (oxLDL) and thiobarbituric acid reactive substances (TBARS) to characterize lipid peroxidation. PATIENTS AND METHODS: 74 hemodialized (HD), 171 renal transplanted patients (TRX), and 110 healthy controls (C) were involved in the study. PON1 activity and TBARS levels were measured spectrophotometrically. OxLDL level was determined with sandwich ELISA. RESULTS: There was a negative correlation between PON1 activity and cystatin C level. Homocysteine level correlated negatively with PON1 activity, and positively with cystatin C level. OxLDL and TBARS levels were significantly higher in the HD and TRX groups compared to C. CONCLUSIONS: Cystatin C may be a good predictive factor not only for homocysteine levels but for the antioxidant status in patients with renal failure and renal transplantation.

The effect of frequent or occasional dialysis-associated hypotension on survival of patients on maintenance haemodialysis.

BACKGROUND: While frequent or occasional symptomatic intradialytic hypotension (IDH) may influence patient well-being, its effects on survival-independent of comorbidities-has not previously been investigated. In this study, therefore, our objective was to assess the effect of frequent IDH (f-IDH) or occasional IDH (o-IDH) on survival. METHODS: During a 10 month run-in period in 1998, 77 patients with f-IDH (> or =10 hypotensive events/10 months, responding only to medical intervention) and 101 patients with o-IDH (1 or 2 events/10 months) were identified among all 958 patients of a dialysis network. Eighty-five patients who had no hypotensive episodes (no-IDH) during this run-in phase served as controls. Patients were followed for a median of 27 months (range: 0.3-37) and survival of patients in the three groups was compared by log-rank test. Independent association of f-IDH and o-IDH with survival, compared with no-IDH, was assessed by a proportional hazards model that included patient demographics, laboratory data and antihypertensive medication as well as comorbidity. RESULTS: Forty-five patients (58%) with f-IDH, 47 (47%) with o-IDH and 33 (39%) with no-IDH died during the follow-up. Mortality rates (deaths/100 patient years) were 37 (log-rank P = 0.013 vs no-IDH), 26 (log-rank P = 0.375 vs no-IDH) and 21 in the three groups, respectively. This indicates significantly decreased survival in patients with f-IDH as compared to those with no-IDH. In multivariate proportional hazards regression, however, where age, sex, time spent on dialysis, presence of coronary heart disease, diabetes, Kt/V, albumin level and use of beta-blockers, calcium-channel blockers and long-acting nitrates has been adjusted for, neither f-IDH nor o-IDH was associated with survival. CONCLUSIONS: Mortality in patients with f-IDH is significantly higher than in those without such events. After adjustments for covariates, however, there is no independent effect of frequent or occasional episodes of IDH on mortality.