Background/Purpose: Hyperuricemia and gout are common in patients with chronic kidney disease (CKD), some ultimately requiring replacement therapy. Serum urate (SU) levels appear to achieve proper control under hemodialysis [1], making urate-lowering drugs (ULD) unnecessary in this setting. Scant data is available for peritoneal dialysis (PD). The aim of the present study was to assess SU levels and urate clearance in patients with CKD under PD.

Methods: A cross-sectional, monocentric study was performed, enrolling all twenty subjects followed in a PD unit during the study period (2018 Jan-Feb). Treatment modalities employed were continuous ambulatory peritoneal dialysis (CAPD) [n=6]; night intermittent peritoneal dialysis (NIPD) [n=3]; and continuous cyclic peritoneal dialysis (CCPD) [n=11]. Blood, 24h urine and dialysis fluid tests were requested in order to measure SU levels (primary outcome variable) and to estimate urate clearance (total, renal, and peritoneal) and residual kidney function (RKF), according to current guidelines [2]. Hyperuricemia was considered as SU >6.8mg/dl. Demographic, clinical and PD-related variables were also collected to assess factors associated with being on SU target (<6.0 mg/dl). For outcome variables, 95% confidence intervals (95%CI) were estimated, and non-parametric tests (Mann-Whitney U’s, Kruskal-Wallis, chi-square, and Fisher’s exact) were used to evaluate associations.

Results: Median (IQR) age was 53.5 years (42.3-63.3), being 65% men. Sixty-five percent were on furosemide, and median RKF was 4.7 ml/min/1.73m² (2.1-5.8). Half of subjects were hyperuricemic before initiating PD, only three (15%) reported gout. Urate-lowering drugs (ULD) were currently used in nine patients (45%), mostly allopurinol (n=8, at 100-150 mg/d), febuxostat in one (40 mg/d). In the sample, median SU levels were 5.4 mg/dl [95%CI 4.8-6.0], being 90% <6.8 mg/dl, and 80% <6.0 mg/dl. SU levels did not statistically varied according to the use of ULD (5.6 vs 4.2 mg/dl respectively, p=0.056). Median peritoneal urate clearance was 3.0 ml/min/1.73m² [95%CI 2.5-3.5], that accounted for 71.4% of total urate clearance (4.2 ml/min/1.73m², 95%CI 3.6-4.6). Explanatory variables that significantly associated with a SU on target were peritoneal urate clearance (3.2 vs 2.0 ml/min/1.73m², p=0.006), RKF (4.0 vs 6.4 ml/min/1.73m², p=0.032), and the use of CCPD modality (100% vs 0%, p=0.008). CCPD modality also showed significantly higher peritoneal urate clearance compared to CAPD and NIPD (3.7, 2.7, and 1.3 ml/min/1.73m², respectively, p=0.011).

Conclusion: Most CKD patients under PD showed SU levels on target, suggesting that PD is effective for hyperuricemia management. ULDs appear then unnecessary in this setting. The CCPD modality showed the best results in terms of urate levels and its clearance, finding that may be of interest for CKD patients with gout.

References: [1] Arthritis Rheumatol. 2016;68suppl10: abstract #205. [2] Clinical practice guidelines for peritoneal adequacy, update 2006. Am J Kidney Dis. 2006;48 Suppl1:S91.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/serum-urate-ant-its-clearance-in-patients-with-chronic-kidney-disease-under-peritoneal-dialysis/