Assessing the Validity of Adjusted Urinary Urea Nitrogen as an Estimate of Total Urinary Nitrogen in Three Pediatric Populations

Boehm, Kristi A.; Helms, Richard A.; Storm, Michael C.

doi:10.1177/0148607194018002172

Cited by 14 publications

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“…Total nitrogen appearance (TNA) is the sum of all outputs of nitrogen from the body, dialysate, urine and feces, in the form of urea, protein, peptides, amino acids and all other nitrogencontaining products, and in steady-state patients, TNA plus any unmeasured nitrogen losses should roughly equal the total nitrogen intake. Because the final product of protein catabolism is urea, and nitrogen intake is almost entirely from protein, in steady state conditions protein intake can be estimated from TNA [29,31]. UUN has often been used to approximate total urinary nitrogen (TUN), because the laboratory methods, like the Kjeldahl method, to measure TUN are time consuming and involve the use of corrosive materials.…”

Section: Discussionmentioning

confidence: 99%

“…The fourth equation detailed above was used in this study, multiplying UUN 1.25, assuming that UUN composes approximately 80% of TUN, and then correcting by 6.25 to express TUN as protein. A second adjustment is required to compensate for insensible nitrogen losses, which can be obtained by multiplying the weight in kg by 0.045 [30,31]. Stool nitrogen losses were approximated to circumvent the problem of extended stool collections, as pointed out in equation 4.…”

Section: Discussionmentioning

confidence: 99%

“…Stool nitrogen losses were approximated to circumvent the problem of extended stool collections, as pointed out in equation 4. This is a common practice in nitrogen balance studies, assuming approximately 40-60 mg/kg of daily fecal losses of nitrogen and 15 mg/kg of daily cutaneous losses [31,32]. The resultant value should closely reflect daily protein catabolism, and when subtracted from DPI, will express the nitrogen balance for each patient [30,34].…”

Section: Discussionmentioning

confidence: 99%

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Kt/V and nPNA in pediatric peritoneal dialysis: a clinical or a mathematical association?

et al. 2005

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The relationship between dialysis dose and nutrition is a field of particular interest in chronic pediatric dialysis (PD), and a positive correlation between ureaKt/V and nPNA has been published, suggesting a better nutritional status is associated with higher dialysis doses. However, this relationship has also been criticized as being the result of a mathematical coupling resulting from the same variables. The objective of the study was to establish the relationship between dialysis dose (Kt/V) and nutritional variables: daily protein intake (DPI), protein catabolic rate (PCR), protein equivalent of total nitrogen appearance (PNA) and nitrogen balance (NB) in dialyzed children. A cohort, prospective, observational study was carried out, for which 223 biochemical measurements were performed in 20 patients, ages 1 month to 14.3 years old (13 males), under PD for a 12-month period of follow-up. Monthly residual and total ureaKt/V, DPI, PCR, nPNA and NB were calculated, and the correlation between Kt/V and the nutritional parameters was evaluated. The Borah equation was used to calculate the nPNA. The data are reported as the mean plus or minus the standard error. All statistical comparisons were done with a paired t test, and two-way ANOVA for repeated measures was used to calculate correlations. A P <0.05 was considered significant. Mean total and residual Kt/V was 3.4+/-1.3 and 1.69+/-1.27, respectively; nPNA and PCR were 1.38+/-0.44 and 1.39+/-0.43 g/kg/day, daily protein intake (DPI) was 3.25+/-1.27 g/kg/day, and NB showed a value of 1.86+/-1.25 g/kg/day. A significant positive correlation was found between Kt/V and DPI, PCR, DPC and nPNA (all values P <0.0001), but no correlation was found between total and residual Kt/V vs. nitrogen balance ( P:ns). Total Kt/V showed a significant positive correlation with nPNA, but it did not show any correlation with nitrogen balance, suggesting that the relationship with nPNA is the result of a mathematical association calculated from the same variables.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Kt/V and nPNA in pediatric peritoneal dialysis: a clinical or a mathematical association?

et al. 2005

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“…Other studies seeking a formula to calculate nitrogen losses avoiding direct nitrogen measurements have been performed in normal children [7] and in adults on continuous ambulatory peritoneal dialysis [2][3][4], but no studies have investigated the reliability and consistency of the proposed models in different samples of patients. Moreover, no such studies have been performed in pediatric patients on CPD.…”

Section: Discussionmentioning

confidence: 99%

“…The available pediatric studies did not consider the use of mathematical models to predict nitrogen losses in uremic children, although this has already been investigated in normal children and in children with non-renal diseases [7]. Formulae predicting nitrogen losses from measurement of nitrogenous compounds in adults treated with CPD have been proposed in a few studies [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

Models to assess nitrogen losses in pediatric patients on chronic peritoneal dialysis

Edefonti¹,

Picca

Damiani

et al. 2000

Pediatr Nephrol

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To develop models to estimate nitrogen (N) losses of children on chronic peritoneal dialysis (CPD) from easily measurable indexes and laboratory tests, we measured the N content and all nitrogenous compounds in dialysate (D), urine (U), and feces over 3 days in 19 pediatric patients on CPD. Total measured N losses (TNm) were 5.56+/-2.26 g/day (69.9+/-11.1% in dialysate, 16.3+/-10.6% in urine, and 13.6+/-4.6% in feces). Correlation coefficients between measured dialysate and urinary N losses and the single nitrogenous compounds indicated values of over 0.9 only for urea in dialysate and urine; fecal N losses correlated well with body surface area (BSA). Taking into account these correlations, we developed a univariate additive model and three multivariate models to predict total estimated N losses (TNe). The best prediction of TNm was obtained with model 3, which considered not only urea output in dialysate and urine but also dialysate protein loss and BSA: TNe (g/day)=0.03+/-1.138 UN urea+0.99 DN urea+1.18 BSA+0.965 DN protein. A confirmatory analysis performed on a second group of 23 pediatric patients on CPD, using all four models, showed a higher percentage of studies with a relative difference between TNm and TNe less than 10% for model 3 than for the other models. Thus, N losses of pediatric patients on CPD can be estimated from measured urea and protein losses in dialysate and urea loss in urine, together with BSA.

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Plasma Citrulline Concentrations in Neonates With or Without Gastrointestinal Disease During Periods of Parenteral and Enteral Nutrition

Herrera

Talati

Helms

2019

J Parenter Enteral Nutr

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Introduction: Citrulline is synthesized primarily in enterocytes. Retrospective work revealed higher plasma concentrations in patients without gastrointestinal (GI) disease than in those with GI disease, regardless of bowel resection, leading us to speculate whether it could be used as a marker of gut function prospectively. Our purpose was to analyze plasma citrulline in these patients, comparing a period of exclusive parenteral nutrition (PN) vs both PN and enteral nutrition (PN/EN). Methods: Premature neonates were included in this study. Plasma samples were collected during 2 periods, PN and PN/EN. They were classified into groups: patients without GI disease (Group 1), patients with GI disease without resection (Group 2), and patients with GI disease and resection (Group 3). Plasma was analyzed by high-performance liquid chromatography and tandem mass spectrometry (LC-MS/MS). Data were described as median with ranges. Results: Fifty patients were recruited for this study, from which 164 samples were obtained and analyzed by LC-MS. Median plasma citrulline concentrations were 12.3 (5.6-39.4) µmol/L, 14.9 (6.8-39.8) µmol/L, and 10.8 (2.0-23.6) µmol/L for Groups 1, 2, and 3, respectively. After Bonferroni correction, only Group 3 had a significantly different median from the others. No differences were observed within periods of nutrition (PN vs PN/EN). Postconceptual age (PCA), among others, was assessed to determine differences for which the former demonstrated significance. Conclusion: Premature neonates with bowel resection had lower plasma citrulline concentrations, confirming its role as gut mass marker, though without differences during transitional feeding. PCA may affect expression of this protein. (JPEN J Parenter Enteral Nutr. 2019;43:977-985) Clinical Relevancy StatementThere is a paucity of biomarkers of intestinal function for the neonatal population that are practical and less invasive than those currently used in pediatric patients. After initial gastrointestinal insult/surgery, clinicians can struggle with finding the appropriate time to start enteral feedings pend-From the

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Assessing the Validity of Adjusted Urinary Urea Nitrogen as an Estimate of Total Urinary Nitrogen in Three Pediatric Populations

Cited by 14 publications

References 13 publications

Kt/V and nPNA in pediatric peritoneal dialysis: a clinical or a mathematical association?

Kt/V and nPNA in pediatric peritoneal dialysis: a clinical or a mathematical association?

Models to assess nitrogen losses in pediatric patients on chronic peritoneal dialysis

Plasma Citrulline Concentrations in Neonates With or Without Gastrointestinal Disease During Periods of Parenteral and Enteral Nutrition

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