Routine Kt/V and Normalized Protein Nitrogen Appearance Rate Determined From Conductivity Access Clearance With Infrequent Postdialysis Serum Urea Nitrogen Measurements

Abstract

Rationale & objectives Conventional monitoring of hemodialysis dose is implemented using urea kinetic modeling based on single-pool Kt/V, which requires both pre- and postdialysis serum urea nitrogen (SUN) measurements. We compared this conventional approach to one in which Kt/V is calculated using conductivity clearance, thereby reducing the need for regular postdialysis SUN measurements. Study design Comparative study of 2 diagnostic tests. Setting & participants Prevalent patients receiving maintenance hemodialysis for at least 2 years for whom both urea reduction ratio (URR) and average conductivity clearance (Kecn) were measured. Tests compared During the initial 8 months (baseline interval), average Kecn and URR were used to calculate a median patient-specific, modeled, calibration solute distribution volume (Vcal). During months 9 to 16 (period 1) and 17 to 24 (period 2), Kt/V was conventionally computed using URR and also by a new method using Vcal and Kecn without postdialysis SUN values. We examined the percentage error between these 2 methods of calculating Kt/V. Outcomes Concordance between the 2 methods of calculating Kt/V. Results Among 1,093 patients, mean individual-level median single-pool Kt/V values derived using the conventional method during the baseline interval, period 1, and period 2 were 1.62±0.24 (SD), 1.66±0.24, and 1.67±0.24, respectively. During periods 1 and 2, patient-level median Kt/V values derived using Kecn were 1.64±0.24 and 1.65±0.24, resp…