Reduced serum urate concentrations despite unchanged allopurinol dosing in gout patients commenced on dialysis: a retrospective chart review

Aim: People with kidney failure are at increased risk of gout-related hospitalisations and mortality. Whilst dialysis enhances urate removal and reduces circulating oxypurinol (allopurinol's active metabolite), its effect on achieving target serum urate concentrations (< 0.36 mmol/L) and implications for gout management remain unclear. This study aimed to evaluate serum urate concentrations and allopurinol dosing following commencement of dialysis. Methods: We conducted a retrospective chart review of adults prescribed allopurinol at a dialysis Centre in New South Wales, Australia, between 01/06/2019 and 30/06/2024. Eligible patients had at least one serum urate concentration recorded after commencing dialysis. Data collected included patient demographics, dialysis modality, allopurinol dosing, and serum urate concentrations, spanning from pre-dialysis to up to 5 years post-commencing dialysis. Results: Forty-five patients (18 haemodialysis [HD], 27 peritoneal dialysis [PD]) were included. Most HD patients (61%) received thrice-weekly haemodiafiltration with high-flux dialysers; 59% of PD patients used automated PD. Allopurinol doses (100–300 mg daily, mostly 100 mg) remained unchanged from pre-dialysis in 93% (42/45). At 4 (0.25–38) months post-dialysis, median serum urate concentrations declined compared to pre-commencing dialysis (HD: 0.31 vs. 0.51 mmol/L, p = 0.031; PD: 0.33 vs. 0.53 mmol/L, p < 0.001). Target serum urate concentrations were reached at least once in 60% of HD and 78% of PD patients. Conclusion: Serum urate concentrations declined after starting dialysis with unchanged allopurinol dosing, suggesting dialysis independently contributes to urate reduction. These findings support re-evaluating allopurinol dose in patients after commencing dialysis, including de-prescribing allopurinol in those who consistently achieve target urate concentrations.