#1615 Working without peritoneal dialysate and urine collections during the COVID-19 pandemic: how to assure sufficient small solute removal

Abstract Background and Aims The guidelines of the International Society of Peritoneal Dialysis suggest regular control of small solute removal. During the COVID-19 pandemic we did not perform additional controls of dialysis adequacy in our peritoneal dialysis patients. We judged patients according symptoms and serum urea levels. In this retrospective study, we aimed to evaluate whether the measurement of serum urea alone might indicate sufficient small solute removal in peritoneal dialysis patients. Method In 216 adult PD patients (139 males, 77 females, median age 64 years, median BMI 26.7) Kt/V urea (renal and peritoneal) was registered together with anthropometric and laboratory data during the first two years of PD therapy. Patients presenting urea values between 100 and 250 mg/dl were included in the statistical analysis, thus resulting in the evaluation of 410 measurements (265 in male, 145 in female patients). Urea distribution volume was calculated using the formula of Watson and Watson. The measurement of urea in blood and urine was performed by a standard kinetic test with urease. Results Serum urea correlated significantly to Kt/V urea (r = −0.28, p < 0.01), whereas significance was not reached in female patients (male patients: r = −0.35, p < 0.01; female patients; r = −0.14, p = 0.13). Kt/V urea of at least 1.7 is achieved in male patients presenting serum urea values lower than 160 mg/dl (95% confidence interval), whereas in female patients apparently presenting serum urea values lower than 200 mg/dl (95% confidence interval). This difference is due to the distinct sex specific urea distribution volume (median value: male patients 40.8 liters, female patients 31.8 liters) and to the absence of a significant correlation between serum urea and Kt/V urea in female patients. Conclusion Serum urea values below 160 mg/dl in male peritoneal dialysis patients are roughly indicating sufficient small solute removal, whereas a clear relation between serum urea and Kt/V urea was not present in female patients in our study population.