Kt/V Calculator Daugirdas

The Kt/ V in dialysis is used for the measurement of the dialysis efficacy. It describes the rate of removal of the excessive fluids/substances (K) in a given treatment (t) of a given patient (V). This index is probably the most popular system to assess the dialysis dose.

The abbreviation itself stands for:

• K – dialyzer clearance – blood passage
• t – duration of dialysis in minutes
• V – volume of body water

This value is dimensionless - is not based on any unit and cannot be calculated using its separate parts and their units.

The Kt/ V system, however, may disadvantage women and smaller people and result in worse dialysis results in these groups of patients - this difference is caused by the variances of their body water content.

Want to know more? How about checking our other kidney-related tools, such as GFR calculator and Urine output calculator?

• The dialysis is considered efficient when Kt/V is greater or equal to 1.2. That's the minimum value that must be kept at all times. All the values that fall below that range are a sign of the flawed process of hemodialysis therapy.

• The peritoneal dialysis target Kt/V is equal to 1.7 weekly (according to the International Society of Peritoneal Dialysis).

However, the patient's treatment should be adjusted to the Kt/V values of more than the recommended target!

It's a precaution used to ensure that the process is indeed of appropriate quality - it's crucial since this variable is directly related to the patient's future outcomes and is correlated to survival!

💡 Current guidelines recommend the weekly Kt/V in Acute Kidney Injury to be at least 3.9

The Kt/ V calculator displays your results along with its basic efficacy evaluation.

Our tool requires you to know three fundamental lab findings:

• Kt/ V urea - both pre and post dialysis level of urea
• Volume of removed ultrafiltrate

You may read some more about these values using FEUrea calculator and BUN/ creatinine ratio calculator.

Kt/ V is considered to be of a better value and more accurate than the URR.

Why is Kt/V better?

Even that both of these values are closely related, the Kt/ V system takes into account two additional variables:

• Urea removed with the fluid during the dialysis
• Urea produced by the body during dialysis

The measurement of fluid removed during dialysis using the Kt/ V is also essential because the excessive amount of fluids accumulated in the patients' bodies might cause inevitable harm to their cardiovascular system.

The KDOQI guidelines recommends the Kt/V to be the primary measure of adequacy.

Our standard Kt/ V calculator uses the following equation:

Kt/V = -ln((Post BUN/Pre BUN)- 0.03) + (4 - 3.5 × (Post BUN/Pre BUN)) × (UF/Weight)

Where:

• Post BUN means the level of post-dialysis Blood Urea Nitrogen, given in milligrams per deciliter (mg/dL).

• Pre BUN means the level of pre-dialysis Blood Urea Nitrogen, given in milligrams per deciliter (mg/dL).

• UF stands for the volume of removed ultrafiltrate, given in liters (L).

• Weight stands for the post-dialysis weight of a subject, given in kilograms (kg).

• ln stands for the logarithm with the base of e → the natural logarithm.

Remember: all multiplications and divisions have a priority over adding and subtractions and should always be calculated first.