How does peritoneal dialysis (PD) contribute to the development of gout?

Peritoneal Dialysis and Gout: Mechanisms and Management

Peritoneal dialysis contributes to gout development primarily through inadequate clearance of uric acid compared to hemodialysis, with peritoneal dialysis removing only about 70% of total uric acid clearance needed to maintain target levels. 1

Mechanisms of Gout in Peritoneal Dialysis Patients

• Peritoneal dialysis (PD) provides insufficient uric acid clearance compared to hemodialysis, leading to hyperuricemia in many patients 1, 2
• While PD does remove uric acid, it accounts for only about 70% of total uric acid clearance in these patients, often resulting in suboptimal control 1
• Hyperuricemia is a direct cause of gout through the formation and deposition of monosodium urate crystals in joints 3
• The prevalence of gout is significantly higher in PD patients (21%) compared to hemodialysis patients (13%), highlighting the relationship between PD and gout 4

Clinical Implications and Risk Factors

• Higher serum uric acid levels in PD patients are independently associated with increased all-cause mortality 5
• PD patients with the highest quartile of uric acid levels have nearly three times higher mortality risk compared to those with moderate levels (HR 2.96,95% CI 1.29-6.80) 5
• Risk factors for hyperuricemia in PD patients include:
  • Declining residual kidney function 6
  • Inadequate dialysis prescription (Kt/Vurea below target of 2.0) 6
  • Protein-rich diet increasing uric acid production 6

Management Strategies

• Continuous cycling peritoneal dialysis shows higher uric acid clearance and better target achievement compared to other PD modalities 1
• Urate-lowering medications may be necessary, but dosage adjustments are crucial:
  • Allopurinol doses should be reduced by 50-60% compared to patients with normal kidney function 2
  • Oxypurinol (active metabolite of allopurinol) is removed by peritoneal dialysis, accounting for more than 50% of its clearance 2
• Only about half of PD patients with gout history receive appropriate urate-lowering therapy, suggesting undertreatment 4

Monitoring and Optimization

• Regular monitoring of serum uric acid levels is essential, with target levels below 6 mg/dL 1
• Assess dialysis adequacy regularly, ensuring Kt/Vurea remains at or above 2.0 per week 6
• Consider increasing dialysis dose if uric acid levels remain elevated despite medication 7
• Monitor for symptoms of gout and initiate appropriate treatment promptly 4

Clinical Pearls and Pitfalls

• Despite elevated uric acid levels, the frequency of acute gouty attacks may paradoxically decline in advanced kidney disease, potentially leading to underdiagnosis 3
• Gout is likely underreported in the PD population, requiring heightened clinical awareness 4
• When managing gout in PD patients, consider the cardiovascular implications of hyperuricemia, as it may contribute to the high cardiovascular mortality in this population 3, 5
• Avoid excessive protein restriction when attempting to lower uric acid, as malnutrition is a significant risk in PD patients 6