Biomaterial Database

Urea and nitrogen excretion in pediatric peritoneal dialysis patients. 2000

S R Mendley, and N L Majkowski

University of Maryland School of Medicine, Baltimore, Maryland 21201-1595, USA. smendley@peds.umaryland.edu

BACKGROUND Adequate nutrition is critical to the care of children with end-stage renal disease, and failure to reach the target dietary intake is associated with growth failure. Prospective studies of urea and nitrogen output in adults have led to the derivation of quantitative relationships, which allow assessment of dietary protein intake when only urea appearance is known. Such a clinically useful relationship has not been defined in children receiving chronic peritoneal dialysis (PD). METHODS We studied 18 pediatric PD patients (ages 0.8 to 14.3 years) on 132 occasions and determined norms of urea nitrogen appearance (UNA), total nitrogen appearance (TNA), and nonurea nitrogen appearance (NUNA). We stratified data on UNA, TNA, NUNA, nonprotein nitrogen appearance, and the protein equivalent of nitrogen appearance by age groups (0 to 5, 6 to 10, and 11 to 15 years of age) and demonstrated significant differences. In addition, dietary protein and energy intake were measured in the outpatient setting with food scales and dietitian interviews, and the results were stratified by age, presence of residual renal function, and recombinant human growth hormone (rhGH) therapy. RESULTS UNA (3.05 +/- 1.38 g/day, 103 +/- 42 mg/kg/day) and TNA (4.67 +/- 1.86 g/day, 159 +/- 52 mg/kg/day) varied significantly between different age groups. NUNA in pediatric subjects (56 +/- 24 mg/kg/day) was significantly greater than previously published adult norms. A linear relationship was defined between UNA and TNA that was specific to pediatric PD patients [TNA (g/day) = 1.26(UNA) + 0.83]. When the relationship was scaled to body mass, the y intercept was significantly different in the youngest subjects [TNA = 1.03 (UNA) + 0.02 (weight in kg) + 0.56 (for subjects age 0 to 5) or 0.98 (for subjects age 11 to 15 or 6 to 10), r2 = 0.91]. Dietary protein intake was significantly greater in subjects receiving rhGH therapy, although nitrogen excretion was unchanged. CONCLUSIONS Markers of protein metabolism in pediatric PD patients are age dependent and differ from adult values. An age-specific relationship between TNA and UNA is defined for pediatric subjects; it does not vary with rhGH or the presence of residual renal function.

UI	MeSH Term	Description	Entries
D007223	Infant	A child between 1 and 23 months of age.	Infants
D007676	Kidney Failure, Chronic	The end-stage of CHRONIC RENAL INSUFFICIENCY. It is characterized by the severe irreversible kidney damage (as measured by the level of PROTEINURIA) and the reduction in GLOMERULAR FILTRATION RATE to less than 15 ml per min (Kidney Foundation: Kidney Disease Outcome Quality Initiative, 2002). These patients generally require HEMODIALYSIS or KIDNEY TRANSPLANTATION.	ESRD,End-Stage Renal Disease,Renal Disease, End-Stage,Renal Failure, Chronic,Renal Failure, End-Stage,Chronic Kidney Failure,End-Stage Kidney Disease,Chronic Renal Failure,Disease, End-Stage Kidney,Disease, End-Stage Renal,End Stage Kidney Disease,End Stage Renal Disease,End-Stage Renal Failure,Kidney Disease, End-Stage,Renal Disease, End Stage,Renal Failure, End Stage
D008297	Male		Males
D009584	Nitrogen	An element with the atomic symbol N, atomic number 7, and atomic weight [14.00643; 14.00728]. Nitrogen exists as a diatomic gas and makes up about 78% of the earth's atmosphere by volume. It is a constituent of proteins and nucleic acids and found in all living cells.
D010530	Peritoneal Dialysis	Dialysis fluid being introduced into and removed from the peritoneal cavity as either a continuous or an intermittent procedure.	Dialyses, Peritoneal,Dialysis, Peritoneal,Peritoneal Dialyses
D001835	Body Weight	The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.	Body Weights,Weight, Body,Weights, Body
D002648	Child	A person 6 to 12 years of age. An individual 2 to 5 years old is CHILD, PRESCHOOL.	Children
D002664	Child Nutritional Physiological Phenomena	Nutritional physiology of children aged 2-12 years.	Child Nutrition Physiology,Child Nutritional Physiology Phenomena,Nutrition Physiology, Child,Child Nutritional Physiology,Child Nutritional Physiology Phenomenon,Nutritional Physiology, Child,Physiology, Child Nutrition,Physiology, Child Nutritional
D002675	Child, Preschool	A child between the ages of 2 and 5.	Children, Preschool,Preschool Child,Preschool Children
D005260	Female		Females