0.80
0.60
0.40
0.50
0.60
URR
0.70
0.80
We have found that the Keshaviah Quick Kt/V formula most closely correlates with both of the
more complex Kt/V calculations that Spectra offers - the Daugirdas II Natural Log and Depner
Full UKM Kt/V (see Figures 2 & 3).
Comparison of Kt/V Formulas to UKM Kt/V
1500 Patient Results
Comparison of Kt/V Formulas to UKM Kt/V
0.6 to 2.0
2.20
2.20
2.00
2.00
1.80
1.80
1.60
1.60
1.40
1.40
1.20
1.00
1.20
0.80
1.00
Depner Full UKM
118
115
121
112
109
106
97
103
94
100
91
88
85
82
79
76
73
70
67
64
61
58
55
52
49
46
43
40
37
34
31
28
25
22
19
16
7
13
4
0.40
10
17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117
1
0.80
0.60
Depner Full UKM
Daugirdas II
Natural Log
(Post BUN/Pre BUN-0.008 x t) +
[4-3.5 x (Post BUN/Pre BUN)] x UF / Wt
Daugirdas II
Natural Log
(Post BUN/Pre BUN-0.008 x t) +
[4-3.5 x (Post BUN/Pre BUN)] x UF / Wt
Jindal
0.04*URR-1.2
Jindal
0.04*URR-1.2
Basile
0.023*URR-0.284
Basile
0.023*URR-0.284
Depner
0.026*URR-0.49
Depner
0.026*URR-0.49
Keshaviah
1.162*In(Pre/Pst)
Keshaviah
1.162*In(Pre/Pst)
Figure 2
Figure 3
References
1 Daugirdas JT: Second generation logarithmic estimates of single-pool variable volume Kt/V: An analysis of error. J Am Soc Nephrol, 4:1205-1213, 1993.
2 Keshaviah, PR, Hanson, GI, Berkseth, RO and Collins, AJ 1988. A simplified approach to monitoring in vivo therapy prescription. Trans.Am. Soc. Artif.
Organs, 34:620–2.
3 National Kidney Foundation. 1997. “NKF-DOQI clinical practice guidelines for hemodialysis adequacy”. Am. J. Kidney Dis., 30 (Suppl):S15–S66.
4 National Kidney Foundation. 2006. “NKF-DOQI clinical practice guidelines for hemodialysis adequacy, Update 2006”. Am. J. Kidney Dis., 48 (Suppl):
S17:22-28.
5 Depner, TA 1994. Assessing adequacy of hemodialysis urea modeling. Kidney Int., 45:1522–35.
Spectra Laboratories, Inc.
525 Sycamore Drive • Milpitas, CA 95035 • 800-433-3773
8 King Road • Rockleigh, NJ 07647 • 800-522-4662
www.spectra-labs.com
KDOQI™ is a trademark of the National Kidney Foundation, Inc.
© 2013 Fresenius Medical Care Holdings, Inc. All rights reserved.
Spectra and the Spectra logo are trademarks of Fresenius
Medical Care Holdings, Inc. or its affiliated companies.
All other trademarks are the property of their respective owners.
KTVBULLETIN_EXT Rev. 7/13
Kt/V Calculations for
the Assessment of
Hemodialysis Adequacy
Kt/V Calculations for the Assessment of
Hemodialysis Adequacy
Although the National Kidney Foundation KDOQI™
Clinical Practice Guidelines recommend full kinetic
modeling as the preferred method for determining
dialysis efficiency4, simpler Kt/V equations that
correlate with the Urea Kinetic Modeling (UKM)
Kt/V are also available. Equations that include
natural log function are preferable because they
more closely account for changes that take place
during the dialysis session.
The most common estimation of dialysis efficiency
is the Urea Reduction Ratio, or URR. BUN is used
as a marker for uremia. The ratio is calculated by
taking the amount of BUN present after the dialysis
session (post BUN) and dividing it by the BUN
present prior to the start of the dialysis session
(pre BUN), using the formula:
dialysis, the characteristics of the dialyzer being
used and the change in fluid volume. The Kt/V
calculation, although more accurate than the URR,
is complex and not easily calculated. However, in
its simplest form, the Kt/V is equal to the natural
log of the pre BUN/post BUN. By substitution,
Kt/V relates to URR as the negative natural log
of 1-URR. These basics become important in
deciding upon the calculations used to estimate
dialysis efficiency.
Depner Full UKM
1.162*ln (Pre BUN/Post BUN)
Refer to Reference #5
The table below outlines the patient information
that is required for the different Kt/V calculations.
Quick Kt/V calculations require only pre and post
BUN patient values, whereas the more complex
Kt/V calculations require additional patient
information, such as pre and post weight.
Patient Data Requirements for Kt/V Calculations:
Kt/V
Calculations
0.02
0.00
1.60
Pre BUN
Post BUN
Pre Wt
Post Wt
Depner Full
UKM
√
√
√
√
Daugirdas II
Natural Log
√
√
√
√
Keshaviah
√
√
UF
√
Start
Time
Stop
Time
Frequency
Schedule
√
√
√
√
√
√
Kt/V
1.40
The URR measures two points - the beginning and
end of dialysis. There is no urea in dialysate, so
the differential between the patient’s blood and the
dialysate is greatest during the beginning of the
session and least toward the end of the session.
The URR is a simple average of this differential
between the beginning and end of dialysis.
However, this ratio is not static and changes over
the course of the dialysis session.
Kt/V was first introduced in 1985 and incorporated
the change in urea concentration over the time on
Keshaviah
All of the above calculations are designed for
patients receiving dialysis three times per week,
between 2 and 4 hours per session. Patients
receiving dialysis more than three days per week
should use the Standard Kt/V.
Wt
URR (%) = 100 x (1 - (Post BUN/Pre BUN))
Full Kt/V Calculations:
Note that the Quick Kt/V calculation can be
ordered for patients individually, as part of the
patient’s LTO, or on an account basis and reported
any time a pre and post BUN result is reported.
In order to provide an easily calculated
approximation of Kt/V, the URR equation was
modified by measuring patient values, creating
normograms of the patient data (see Figure 1),
and establishing the calculation that best
approximated the measured Kt/V. These formulas,
commonly referred to as “quick” or “bedside”
calculations, provide a simple means to arrive
at Kt/V approximation without any additional
information than the pre and post BUN.
1.80
Quick Kt/V Calculations:
Daugirdas II Natural Log(Post BUN/Pre BUN – 0.008
x t) + [4-3.5 x (Post BUN/Pre
BUN)] x UF/Wt
0.10
0.08
0.06
0.04
There are a number of dialysis adequacy
calculations published in the scientific literature
that provide information regarding the efficiency
of dialysis. These calculations range from “quick”
bedside Kt/V calculations that require only a
pre and post Blood Urea Nitrogen (BUN) result,
to full kinetic modeling calculations that require
additional patient information to calculate the
most accurate Kt/V.
Spectra Laboratories offers the following Kt/V calculations for the assessment of
hemodialysis adequacy:
A “quick” calculation, requiring only a pre and post BUN but incorporating the logarithmic
expression of the change, most easily approximates the calculated Kt/V.
1.20
1.00
0.80
0.60
0.40
0.50
0.60
URR
0.70
0.80
Figure 1: Normogram 4
Because the Keshaviah Quick Kt/V formula also uses the natural log in its calculation,
we have found it most closely correlates with both the complex Kt/V calculations that
Spectra offers - the Daugirdas II Natural Log Kt/V and the Depner Full UKM Kt/V.
CLINICAL PRACTICE GUIDELINES FOR HEMODIALYSIS ADEQUACY, UPDATE 2006
GUIDELINE 2: METHODS FOR MEASURING AND EXPRESSING HEMODIALYSIS DOSE
2.4 The preferred method for measurement of the delivered dose is formal urea kinetic modeling.
Other methods may be used, provided they give similar results and do not significantly
2.20
overestimate the modeled dose.
2.00
1.80
2.20
2.00
1.80
1.60
If you would like to change your account based Kt/V to the Keshaviah formula,
please contact Customer Service:
1-800-433-3773 (Milpitas, CA) • 1-800-522-4662 (Rockleigh, NJ)
Kt/V Calculations for the Assessment of
Hemodialysis Adequacy
Although the National Kidney Foundation KDOQI™
Clinical Practice Guidelines recommend full kinetic
modeling as the preferred method for determining
dialysis efficiency4, simpler Kt/V equations that
correlate with the Urea Kinetic Modeling (UKM)
Kt/V are also available. Equations that include
natural log function are preferable because they
more closely account for changes that take place
during the dialysis session.
The most common estimation of dialysis efficiency
is the Urea Reduction Ratio, or URR. BUN is used
as a marker for uremia. The ratio is calculated by
taking the amount of BUN present after the dialysis
session (post BUN) and dividing it by the BUN
present prior to the start of the dialysis session
(pre BUN), using the formula:
dialysis, the characteristics of the dialyzer being
used and the change in fluid volume. The Kt/V
calculation, although more accurate than the URR,
is complex and not easily calculated. However, in
its simplest form, the Kt/V is equal to the natural
log of the pre BUN/post BUN. By substitution,
Kt/V relates to URR as the negative natural log
of 1-URR. These basics become important in
deciding upon the calculations used to estimate
dialysis efficiency.
Depner Full UKM
1.162*ln (Pre BUN/Post BUN)
Refer to Reference #5
The table below outlines the patient information
that is required for the different Kt/V calculations.
Quick Kt/V calculations require only pre and post
BUN patient values, whereas the more complex
Kt/V calculations require additional patient
information, such as pre and post weight.
Patient Data Requirements for Kt/V Calculations:
Kt/V
Calculations
0.02
0.00
1.60
Pre BUN
Post BUN
Pre Wt
Post Wt
Depner Full
UKM
√
√
√
√
Daugirdas II
Natural Log
√
√
√
√
Keshaviah
√
√
UF
√
Start
Time
Stop
Time
Frequency
Schedule
√
√
√
√
√
√
Kt/V
1.40
The URR measures two points - the beginning and
end of dialysis. There is no urea in dialysate, so
the differential between the patient’s blood and the
dialysate is greatest during the beginning of the
session and least toward the end of the session.
The URR is a simple average of this differential
between the beginning and end of dialysis.
However, this ratio is not static and changes over
the course of the dialysis session.
Kt/V was first introduced in 1985 and incorporated
the change in urea concentration over the time on
Keshaviah
All of the above calculations are designed for
patients receiving dialysis three times per week,
between 2 and 4 hours per session. Patients
receiving dialysis more than three days per week
should use the Standard Kt/V.
Wt
URR (%) = 100 x (1 - (Post BUN/Pre BUN))
Full Kt/V Calculations:
Note that the Quick Kt/V calculation can be
ordered for patients individually, as part of the
patient’s LTO, or on an account basis and reported
any time a pre and post BUN result is reported.
In order to provide an easily calculated
approximation of Kt/V, the URR equation was
modified by measuring patient values, creating
normograms of the patient data (see Figure 1),
and establishing the calculation that best
approximated the measured Kt/V. These formulas,
commonly referred to as “quick” or “bedside”
calculations, provide a simple means to arrive
at Kt/V approximation without any additional
information than the pre and post BUN.
1.80
Quick Kt/V Calculations:
Daugirdas II Natural Log(Post BUN/Pre BUN – 0.008
x t) + [4-3.5 x (Post BUN/Pre
BUN)] x UF/Wt
0.10
0.08
0.06
0.04
There are a number of dialysis adequacy
calculations published in the scientific literature
that provide information regarding the efficiency
of dialysis. These calculations range from “quick”
bedside Kt/V calculations that require only a
pre and post Blood Urea Nitrogen (BUN) result,
to full kinetic modeling calculations that require
additional patient information to calculate the
most accurate Kt/V.
Spectra Laboratories offers the following Kt/V calculations for the assessment of
hemodialysis adequacy:
A “quick” calculation, requiring only a pre and post BUN but incorporating the logarithmic
expression of the change, most easily approximates the calculated Kt/V.
1.20
1.00
0.80
0.60
0.40
0.50
0.60
URR
0.70
0.80
Figure 1: Normogram 4
Because the Keshaviah Quick Kt/V formula also uses the natural log in its calculation,
we have found it most closely correlates with both the complex Kt/V calculations that
Spectra offers - the Daugirdas II Natural Log Kt/V and the Depner Full UKM Kt/V.
CLINICAL PRACTICE GUIDELINES FOR HEMODIALYSIS ADEQUACY, UPDATE 2006
GUIDELINE 2: METHODS FOR MEASURING AND EXPRESSING HEMODIALYSIS DOSE
2.4 The preferred method for measurement of the delivered dose is formal urea kinetic modeling.
Other methods may be used, provided they give similar results and do not significantly
2.20
overestimate the modeled dose.
2.00
1.80
2.20
2.00
1.80
1.60
If you would like to change your account based Kt/V to the Keshaviah formula,
please contact Customer Service:
1-800-433-3773 (Milpitas, CA) • 1-800-522-4662 (Rockleigh, NJ)
0.80
0.60
0.40
0.50
0.60
URR
0.70
0.80
We have found that the Keshaviah Quick Kt/V formula most closely correlates with both of the
more complex Kt/V calculations that Spectra offers - the Daugirdas II Natural Log and Depner
Full UKM Kt/V (see Figures 2 & 3).
Comparison of Kt/V Formulas to UKM Kt/V
1500 Patient Results
Comparison of Kt/V Formulas to UKM Kt/V
0.6 to 2.0
2.20
2.20
2.00
2.00
1.80
1.80
1.60
1.60
1.40
1.40
1.20
1.00
1.20
0.80
1.00
Depner Full UKM
118
115
121
112
109
106
97
103
94
100
91
88
85
82
79
76
73
70
67
64
61
58
55
52
49
46
43
40
37
34
31
28
25
22
19
16
7
13
4
0.40
10
17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 75 77 79 81 83 85 87 89 91 93 95 97 99 101 103 105 107 109 111 113 115 117
1
0.80
0.60
Depner Full UKM
Daugirdas II
Natural Log
(Post BUN/Pre BUN-0.008 x t) +
[4-3.5 x (Post BUN/Pre BUN)] x UF / Wt
Daugirdas II
Natural Log
(Post BUN/Pre BUN-0.008 x t) +
[4-3.5 x (Post BUN/Pre BUN)] x UF / Wt
Jindal
0.04*URR-1.2
Jindal
0.04*URR-1.2
Basile
0.023*URR-0.284
Basile
0.023*URR-0.284
Depner
0.026*URR-0.49
Depner
0.026*URR-0.49
Keshaviah
1.162*In(Pre/Pst)
Keshaviah
1.162*In(Pre/Pst)
Figure 2
Figure 3
References
1 Daugirdas JT: Second generation logarithmic estimates of single-pool variable volume Kt/V: An analysis of error. J Am Soc Nephrol, 4:1205-1213, 1993.
2 Keshaviah, PR, Hanson, GI, Berkseth, RO and Collins, AJ 1988. A simplified approach to monitoring in vivo therapy prescription. Trans.Am. Soc. Artif.
Organs, 34:620–2.
3 National Kidney Foundation. 1997. “NKF-DOQI clinical practice guidelines for hemodialysis adequacy”. Am. J. Kidney Dis., 30 (Suppl):S15–S66.
4 National Kidney Foundation. 2006. “NKF-DOQI clinical practice guidelines for hemodialysis adequacy, Update 2006”. Am. J. Kidney Dis., 48 (Suppl):
S17:22-28.
5 Depner, TA 1994. Assessing adequacy of hemodialysis urea modeling. Kidney Int., 45:1522–35.
Spectra Laboratories, Inc.
525 Sycamore Drive • Milpitas, CA 95035 • 800-433-3773
8 King Road • Rockleigh, NJ 07647 • 800-522-4662
www.spectra-labs.com
KDOQI™ is a trademark of the National Kidney Foundation, Inc.
© 2013 Fresenius Medical Care Holdings, Inc. All rights reserved.
Spectra and the Spectra logo are trademarks of Fresenius
Medical Care Holdings, Inc. or its affiliated companies.
All other trademarks are the property of their respective owners.
KTVBULLETIN_EXT Rev. 7/13
Kt/V Calculations for
the Assessment of
Hemodialysis Adequacy