Daugirdas Kt/V
Use paired BUN samples and treatment data collected according to your dialysis unit protocol.
About Daugirdas Kt/V
Kt/V is a dimensionless measure used to describe the delivered dose of intermittent hemodialysis. K represents effective urea clearance by the dialyzer, t is treatment time, and V approximates the patient's urea distribution volume. Because directly measuring each term is difficult in routine care, the second-generation Daugirdas equation estimates single-pool Kt/V from pre- and post-dialysis blood urea nitrogen, session duration, ultrafiltration volume, and post-dialysis weight.
The post-dialysis to pre-dialysis BUN ratio supplies most of the clearance information. The time correction accounts for urea generation during treatment, while the ultrafiltration term adjusts for concentration caused by fluid removal. This calculator assumes that liters of net ultrafiltration are approximately equivalent to kilograms of removed fluid. BUN units cancel in the ratio, but the pre- and post-treatment samples must use the same units and must be collected with a consistent, validated sampling technique.
Sampling errors can substantially distort the estimate. Access recirculation, drawing the post sample too soon, failing to slow or stop blood flow according to protocol, shortened treatment, and incorrect treatment records are common concerns. Single-pool Kt/V also does not fully represent post-dialysis urea rebound. Other measures, including equilibrated Kt/V, standard Kt/V, urea reduction ratio, treatment frequency, residual kidney function, volume control, nutrition, and symptoms, may be relevant to adequacy assessment.
For conventional thrice-weekly hemodialysis, clinical programs commonly target a delivered single-pool Kt/V of at least 1.2 per treatment, often prescribing more to allow for variability. Targets differ for pediatric patients, pregnancy, frequent or extended schedules, acute kidney injury, and unusual body composition. A numerical target is only one part of safe dialysis care. The nephrology team should review trends and investigate unexpectedly low or high values rather than acting on a single online calculation. This educational tool cannot verify sample quality, diagnose inadequate dialysis, or recommend a treatment prescription. Patients should not change session time, fluid removal, access management, or attendance based on this result.
Kt/V calculator FAQ
What does a Kt/V of 1.2 mean?
It is a conventional minimum delivered-dose benchmark for many thrice-weekly adult hemodialysis treatments. It does not mean that exactly 120 percent of body water was cleared.
Must BUN be entered in mg/dL?
The ratio is unchanged if both samples use the same concentration unit. The displayed label uses mg/dL to promote consistent entry.
Why is post-dialysis weight used?
It scales the ultrafiltration correction to body size. Use the recorded weight at the end of the same treatment.
Can Kt/V assess peritoneal dialysis?
Not with this Daugirdas calculator. Peritoneal dialysis adequacy uses timed dialysate and urine collections with a different calculation.
Why might my result change unexpectedly?
Sampling technique, access function, treatment time, blood flow, dialyzer performance, and data-entry errors can all affect it. Unexpected changes should be verified by the dialysis team.