Question 1

What is the difference between spKt/V and eKt/V?

Accepted Answer

spKt/V uses a single-compartment model and overestimates the true dose by approximately 0.2 due to urea rebound. The equilibrated Kt/V (eKt/V) accounts for this rebound. Most guidelines use spKt/V targets (≥1.4) with the understanding that eKt/V will be lower.

Question 2

Can Kt/V be too high?

Accepted Answer

Kt/V >1.8 is not associated with additional survival benefit (the HEMO study showed no benefit above spKt/V 1.7). Very high Kt/V may indicate prolonged treatment times, but there is no known harm. The goal is ≥1.4 and well-tolerated treatments.

Question 3

How do I interpret Kt/V in patients with residual kidney function?

Accepted Answer

The standard Kt/V measures only the dialysis component. For patients with significant residual GFR (>2 mL/min), the standard target may be relaxed slightly. The combined kidney and dialysis clearance (standard Kt/V) may better reflect total solute clearance.

Question 4

What factors cause a low Kt/V besides inadequate prescription?

Accepted Answer

Access recirculation (stenosis or poor needle placement), poor blood flow, incorrect blood sampling (dilution from saline), dialyser clotting, and shorter-than-prescribed treatment time due to alarms or hypotension.