Kt/V

Kt/V is a numerical value used in medicine to quantify hemodialysis and peritoneal dialysis treatment adequacy.

Overview

In the context of dialysis, Kt/V is a pseudo-dimensionless number; it is dependent on the pre- and post-dialysis urea concentrations, the volume of distribution of urea (roughly equal to patient's total body water), and the amount of dialysis given. The Kt/V is used primarily to quantify hemodialysis and peritoneal dialysis treatments, but it is also used in the assessment of the adequacy of other forms of renal replacement therapy.

Calculation

The Kt/V is calculated using the formula:

Kt/V = -ln(R - 0.008 * t) + (4 - 3.5 * R) * UF/W

where:

• K is the dialyzer clearance, the rate at which blood flows through the dialyzer, expressed in milliliters per minute (mL/min)
• t is the dialysis time, expressed in minutes
• V is the volume of distribution of urea, roughly equal to patient's total body water, expressed in liters
• R is the ratio of post-dialysis BUN to pre-dialysis BUN
• UF is the volume of fluid removed during dialysis, expressed in liters
• W is the post-dialysis weight, expressed in kilograms

Clinical significance

The Kt/V value is used to guide treatment in individuals undergoing dialysis. A Kt/V of 1.2 or more is generally considered an adequate dose of dialysis, while a Kt/V of less than 1.2 may indicate that the dialysis prescription needs to be adjusted.

See also

• Dialysis
• Urea reduction ratio
• Renal function