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Satko SG, Burkart JM, Bleyer AJ, Jordan JR, Manning T. Frequency and Causes of Discrepancy between Kt/V and Creatinine Clearance. Perit Dial Int 2020. [DOI: 10.1177/089686089901900106] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Objective This study examines the frequency of discrepancy between Kt/V urea and creatinine clearance (Ccr) measurements in patients on peritoneal dialysis (PD) and the reasons for this discrepancy. Design Nonrandomized, retrospective data analysis. Setting Single PD unit of a university teaching hospital. Patients All adult patients receiving PD at our center from January 1995 to December 1996. Methods Actual (a) and desired (d) body weight (BW) were used to calculate urea volume of distribution (V) and body surface area (BSA). Patients were divided into four groups based upon their total small solute clearances (Kt/V and Ccr, normalized by actual weight) and three additional groups based upon actual/desired (a/d) body weight ratio. An additional analysis was performed for the subset of anuric patients. Data collected for all patients included the following: total Kt, total Ccr, 4-hour dialysate/ plasma (D/P) creatinine, serum albumin concentration, duration of PD, actual body weight, age, and height. Results Twenty-three percent of the clearance measurements in our study were discrepant, defined as having values for either Kt/V or Ccr (but not both) above the accepted targets of Kt/V ≥ 2.0/wk and Ccr ≥ 60 L/wk/ 1.73 m2. Patients with both values above target are more likely to have higher residual renal function. Patients who are significantly less than BWd and patients on PD for a longer time are more likely to have adequate Kt/V but not Ccr. Furthermore, patients who are less than 90% or greater than 110% of BWd have markedly different values for Kt/V and Ccr when BWa versus BWd values are used. Conclusions Kt/V and Ccr values are frequently discrepant; a number of factors affect these two measurements to varying degrees, including weight, degree of residual renal function, and duration of PD.
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Affiliation(s)
- Scott G. Satko
- Section on Nephrology, Winston-Salem, North Carolina, U.S.A
| | | | | | - Jean R. Jordan
- Department of Internal Medicine, Wake Forest University School of Medicine, and Piedmont Dialysis Center Inc., Winston-Salem, North Carolina, U.S.A
| | - Thomas Manning
- Department of Internal Medicine, Wake Forest University School of Medicine, and Piedmont Dialysis Center Inc., Winston-Salem, North Carolina, U.S.A
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Affiliation(s)
- Peter G. Blake
- Division of Nephrology, Optimal Dialysis Research Unit, University of Western Ontario, London Health Sciences Centre, London, Ontario, Canada
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Ishikura K, Hataya H, Ikeda M, Honda M. Suitable Dialytic Indicators for Pediatric Peritoneal Dialysis Patients: The Alternative to Creatinine Clearance. Perit Dial Int 2020. [DOI: 10.1177/089686080302300310] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
← Objective Owing to the discord between body weight and body surface area (BSA), creatinine clearance (CCr) is predisposed to be small in pediatric patients on peritoneal dialysis (PD). Alternatively, Kt/V creatinine (Kt/V creat), which is normalized to total body water (TBW) rather than BSA, could be a better dialytic indicator. In this study, the efficiency of dialysis and the nutritional status of pediatric patients on chronic PD were examined, and the utility of dialytic indicators was evaluated. ← Patients and Methods 49 patients under 20 years old, in stable condition, and on PD were analyzed. Weekly total Kt/V of urea (Kt/V urea), CCr, Kt/V creat, and normalized protein equivalent of nitrogen appearance (nPNA) were measured for all patients and for patients under 6 years old. The target value was 2.0/week for Kt/V urea and 60 L/week/1.73 m2 for CCr, as recommended by the Kidney Disease Outcomes Quality Initiative guidelines. The target value for Kt/V creat was set as 1.52/week, using a male model with a height of 170 cm and a body weight of 65 kg. ← Results The mean values of delivered Kt/V urea, CCr, Kt/V creat, and nPNA (and proportion of patients that achieved each target value) for all patients were 2.25 ± 0.57/week (67.4%), 53.8 ± 19.3 L/week/1.73 2m (26.5%), 1.83 ± 0.73/week (65.3%), and 1.11 ± 0.42 g/day, respectively. The values for patients under 6 years old were 2.38± 0.26/week (90.0%), 45.9 ± 12.8 L/week/1.73 2m (10.0%), 1.94 ± 0.51/week (90.0%), and 1.52 ± 0.67 g/day, respectively. Stepwise multiple regression analyses revealed that the relationship between CCr and Kt/V urea was affected by the patient's age. ← Conclusions Our pediatric patients achieved the recommended target value of Kt/V urea. At the same time, the nPNA results reflected the patient's status well. However, CCr appeared to be inappropriate as an indicator for patients under 6 years old. Kt/V creat is suggested to be a better dialytic indicator for these patients.
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Affiliation(s)
- Kenji Ishikura
- Department of Pediatric Nephrology, Tokyo Metropolitan Children's Hospital, Tokyo, Japan
| | - Hiroshi Hataya
- Department of Pediatric Nephrology, Tokyo Metropolitan Children's Hospital, Tokyo, Japan
| | - Masahiro Ikeda
- Department of Pediatric Nephrology, Tokyo Metropolitan Children's Hospital, Tokyo, Japan
| | - Masataka Honda
- Department of Pediatric Nephrology, Tokyo Metropolitan Children's Hospital, Tokyo, Japan
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Tzamaloukas AH, Murata GH, Bernardini J, Malhotra D, Rao P, Piraino B, Oreopoulos DG. Gender Differences in Normalized Clearances in Capd: Role of Body Size and Normalizing Parameters. Perit Dial Int 2020. [DOI: 10.1177/089686089901900216] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Objective To compare raw (not normalized) and normalized urea and creatinine clearances between women and men on continuous ambulatory peritoneal dialysis (CAPD). To study whether potential gender differences are due to the normalization process. Design Retrospective analysis of clearance studies. Setting Dialysis units of four academic medical centers. Participants The study included 302 subjects (135 women and 167 men) on CAPD with four daily exchanges and a 2-L exchange volume. Intervention Measurement of urea and creatinine clearances (261 in women, 352 in men) by standard methods. Body water (the volume of distribution, V, for both urea and creatinine) was estimated by the Watson anthropometric formulas. Main Outcome Measures Comparison of raw and normalized clearances between women and men. Urea clearance was normalized by V (Kt/Vur), while creatinine clearances was normalized by both V (Kt/Vcr) and body surface area (BSA) (Ccr). Results Mean values of weekly total (peritoneal plus renal) raw clearances were higher in men (urea clearance: women 67.1 L, men 77.4 L; Ccr: women 61.7 L, men 78.3 L). Raw renal clearances were higher in men, while raw peritoneal clearances were comparable. Mean weekly total Kt/Vur was higher in women (2.19 vs 1.94 in men), mean weekly total Kt/Vcr did not differ between the genders (women 2.01, men 1.95), while mean weekly Ccr was higher in men (73.0 vs 64.7 L/1.73 m2 in women). When clearances differed, the differences were significant at p < 0.001. Men had greater height and weight, while women had greater body mass index. On the average, V in men exceeded V in women by 31%, while BSA in men exceeded BSA in women by only 12%. Conclusions Normalization of clearances by V creates relatively higher clearance values in women, while normalization by BSA creates relatively higher clearance values in men. Thus the normalization process may create artificial differences in the normalized clearances between genders.
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Affiliation(s)
- Antonios H. Tzamaloukas
- Renal Section and General Internal Medicine Section, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Glen H. Murata
- Veterans Affairs Medical Center and Department of Medicine, University of New Mexico School of Medicine, Albuquerque, New Mexico
| | - Judith Bernardini
- Renal and Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
| | - Deepak Malhotra
- Division of Nephrology, Department of Medicine, Medical College of Ohio, Toledo, Ohio, U.S.A
| | - Panduranga Rao
- Division of Nephrology, University of Toronto Medical School, Toronto, Ontario, Canada
| | - Beth Piraino
- Renal and Electrolyte Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania
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Tzamaloukas AH, Murata GH. Peritoneal Dialysis in Patients with Large Body Size: Can it Deliver Adequate Clearances? Perit Dial Int 2020. [DOI: 10.1177/089686089901900502] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Antonios H. Tzamaloukas
- Sections of Nephrology and General Internal Medicine New Mexico VA Health System and University of New Mexico School of Medicine Albuquerque, New Mexico, U.S.A
| | - Glen H. Murata
- Sections of Nephrology and General Internal Medicine New Mexico VA Health System and University of New Mexico School of Medicine Albuquerque, New Mexico, U.S.A
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Tzamaloukas A, Murata G. Effect of Age on Normalized Small Solute Clearances in Men on Peritoneal Dialysis. Perit Dial Int 2020. [DOI: 10.1177/089686089901900119] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
- A.H. Tzamaloukas
- Renal and General Internal Medicine Sections Veterans Affairs Medical Center 1501 San Pedro, SE Albuquerque, New Mexico 87108 U.S.A
| | - G.H. Murata
- University of New Mexico School of Medicine Albuquerque, New Mexico, U.S.A
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Johansson AC, Samuelsson O, Attman PO, Bosaeus I, Haraldsson B. Limitations in anthropometric calculations of total body water in patients on peritoneal dialysis. J Am Soc Nephrol 2001; 12:568-573. [PMID: 11181805 DOI: 10.1681/asn.v123568] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Having an accurate estimation of total body water (TBW) is essential for the evaluation of dialysis efficacy in peritoneal dialysis (PD) patients. In this study, TBW volumes were measured by tritium dilution (TBW(THO)) in 165 PD patients and compared with TBW calculations according to the Watson formulas. An alternative anthropometric formula based on the present PD population was also developed and validated in an independent sample of 29 PD patients. Furthermore, the relation between TBW(THO) and body surface area (BSA) according to the formula of Gehan was analyzed. Body composition was assessed by a four-compartment model, based on measurements of TBW(THO) and total body potassium. Mean values of TBW by the Watson formulas were almost identical to TBW(THO), and the correlation coefficient for the relationship of calculated to measured volumes was 0.89 (P = 0.001). However, both anthropometric formulas-the Watson formulas as well as the new, alternative one-overestimated TBW in obese patients and vice versa in lean patients. Similarly, TBW was underestimated in patients who were overhydrated. The correlation coefficient between TBW(THO) and BSA was 0.708 for males and 0.797 for females (P = 0.0001 for both). In obese patients, the relationship was even closer (r = 0.924 and 0.911, respectively). In conclusion, anthropometric formulas to calculate TBW showed a considerable intraindividual variability compared with measured values. This was related to body composition features, such as degree of obesity and hydration. In contrast, BSA correlated closely to TBW in obese individuals. TBW as estimated by anthropometric formulas must be analyzed with caution, especially in the very obese or very lean patient.
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Affiliation(s)
| | - Ola Samuelsson
- Department of Nephrology, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Per Ola Attman
- Department of Nephrology, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Ingvar Bosaeus
- Department of Clinical Nutrition, Sahlgrenska University Hospital, Göteborg, Sweden
| | - Börje Haraldsson
- Department of Physiology, Sahlgrenska University Hospital, Göteborg, Sweden
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Abstract
The National Kidney Foundation-Dialysis Outcomes Quality Initiatives guidelines have standardized many aspects of treating end-stage renal disease patients with peritoneal dialysis in an attempt to improve overall patient outcome. While recommending certain total solute clearance goals, the guidelines have also pointed out deficiencies in our knowledge base and precipitated many controversies. Some of these controversies have been resolved while others may have been interpreted wrongly, unnecessarily resulting in transfer of patients from peritoneal dialysis to hemodialysis due to "failure to meet adequacy targets" even when doing well clinically. This report reviews the rationale for the original guidelines and their subsequent modification. It also outlines a rational approach toward prescription modification based on peritoneal physiology. Specific solute clearance target goals discussed are the modifications for continuous ambulatory peritoneal dialysis (CAPD) and cycler peritoneal dialysis (CCPD), and a review of what solute clearance targets subsequent guidelines from other countries have used. Some examples are as follows: new guidelines suggest that solute clearance goals for creatine clearance should differ for low and low-average transporters than for high and high-average transporters (weekly clearance of 50 and 60 1/1.73 m(2), respectively) while Kt/V targets remain unchanged. Also discussed is the rationale for having the same target for patients on CCPD with a mid-day exchange as those for patients on CAPD. We are also reminded that solute clearance is only one aspect of "adequate" dialysis-blood pressure and volume control are equally important, and ways to maintain euvolemia and blood pressure control are discussed in the context of prescription management.
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Affiliation(s)
- J M Burkart
- Department of Internal Medicine/Nephrology, Wake Forest University School of Medicine, Winston-Salem, NC, USA
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Tzamaloukas AH, Murata GH, Malhotra D. Dependence of peritoneal clearances on body size in continuous ambulatory peritoneal dialysis: effect of the normalizing size indicator. ASAIO J 2000; 46:76-80. [PMID: 10667722 DOI: 10.1097/00002480-200001000-00020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
In peritoneal dialysis (PD), small solute clearances are normalized by body water (V) and body surface area (BSA). The purpose of this study was to identify if V or BSA produced stronger associations between body size and normalized clearances. We studied the relationship between four size indicators (V, BSA, height, and weight) and either peritoneal urea clearance normalized to V (Kt/V(ur)) and BSA (C(ur)) or creatinine clearance normalized to V (Kt/V(cr)) and BSA (C(cr)). A total of 613 clearance studies were performed in subjects on continuous ambulatory peritoneal dialysis (CAPD) with four daily exchanges and a 2 L fill volume. As size increased, the normalized peritoneal clearances decreased in a nonlinear fashion (regression: y = b0 + b1x(-1), where x is a size indicator and y is a normalized clearance). Significant (p < 0.001) negative correlations were found between each normalized clearance and each size indicator. However, in each case, the correlation was higher when V, rather than BSA, was used. For example, BSA correlated more closely with K/V(ur)(-0.660) than C(ur)(-0.556), and also with Kt/V(cr)(-0.579) than C(cr)(-0.446). Normalized clearances are smaller in large subjects on CAPD because one mathematic determinant of the clearance, the drain volume (Dv) normalized by V (Dv/V) or BSA (DV/BSA), decreases as size increases. The relationship between Dv/V or Dv/BSA and the size indicators was studied by the same nonlinear regression model. The correlations of the size indicators with Dv/V were also consistently higher than the corresponding correlations with Dv/BSA. In subjects who were on the same PD schedule, the dependence of clearances on size was consistently higher when V, rather than BSA, was the normalizing parameter. Because prescription of the dose of PD is based on body size, there is a practical advantage by using V as the sole normalizing parameter for both urea and creatinine clearance.
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Affiliation(s)
- A H Tzamaloukas
- New Mexico Veterans Affairs Health System, and the Department of Medicine, University of New Mexico School of Medicine, Albuquerque 87108, USA
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10
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Tzamaloukas AH, Murata GH, Piraino B, Malhotra D, Bernardini J, Rao P, Oreopoulos DG. The relation between body size and normalized small solute clearances in continuous ambulatory peritoneal dialysis. J Am Soc Nephrol 1999; 10:1575-81. [PMID: 10405214 DOI: 10.1681/asn.v1071575] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
The normalized peritoneal clearances of small solutes depend on the ratio of their concentration in dialysate and plasma (D/P) and the drain volume (Dv) corrected for some measure of body size such as body water (V) or body surface area (BSA). The clearance formulas (D/P) x (Dv/V) and (D/ P) x (Dv/BSA) can be used to examine why large individuals tend to be underdialyzed. Large people have low normalized drain volumes (Dv/V, Dv/BSA). It is not known whether size affects the D/P ratios. The purpose of this study was to examine the relationship between normalized peritoneal clearances (Kt/Vurea, CCr per 1.73 m2 BSA) and four size indicators (weight, height, V, BSA) in 301 patients on continuous ambulatory peritoneal dialysis (four daily exchanges with 2-L exchange volume) who underwent 613 clearance studies. Highly significant (P < 0.001) nonlinear relationships were found between Kt/Vurea and weight (r2 = 0.371), height (r2 = 0.289), BSA (r2 = 0.436), and V (r2 = 0.527); and between CCr and weight (r2 = 0.178), height (r2 = 0.115), BSA (r2 = 0.199), and V (r2 = 0.151). There were also significant negative correlations between the normalized drain volumes (Dv/V and Dv/BSA) and all four indicators of body size. Raw (not normalized) peritoneal clearances and drain volumes correlated positively with size. However, D/P(urea) or D/P(creatinine) did not vary with any size indicator except for a weak association between D/P(creatinine) and V (r = 0.089, P = 0.028). This association was not confirmed when V was used to stratify subjects into quartiles, and group differences for D/P(creatinine were tested by one-way ANOVA. This study shows that the exclusive cause of the low normalized peritoneal clearances in large subjects on continuous ambulatory peritoneal dialysis is a low normalized drain volume. No evidence was found to indicate that body size influences the D/P ratio of small solutes. The portion of the variance in normalized clearance explained by size varies by size indicator and solute (urea versus creatinine).
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Affiliation(s)
- A H Tzamaloukas
- Veterans Affairs Medical Center and Department of Medicine, University of New Mexico School of Medicine, Albuquerque 87108, USA.
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