Urinary Flow Rates and Urea Excretion Rates in Newborn Infants

Jones, Douglas; Gresham, Edwin L.; Battaglia, Frederick C.

doi:10.1159/000240521

Cited by 28 publications

(5 citation statements)

References 8 publications

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“…No difficulty was found, however, in the ability to respond with a fairly high diuresis. High urinary flow rates in the immediate neonatal period have also been reported by others (35). Moreover, no significant increase in the diuresis was noted during the first months of life (111).…”

Section: Diuresissupporting

confidence: 54%

“…Renal control of sodium homeostasis was studied in 149 infants with a gestational age of [28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] weeks and postnatal age from birth to 13 months of age. Fifty-seven were healthy full-term infants and 44 were healthy preterms.…”

Section: Discussionmentioning

confidence: 99%

“…The diluting some low values were observed, i.e. [25][26][27][28][29][30][31][32][33][34][35] capacity or free water cIearence which is also an index of distal tubular sodium re-:b (mean * 1 SD, ml/hour/1.73 m2.) absorption (5) was supernormal in preterm infants and in newborn full-term infants in the immediate neonatal period (I, 11).…”

Section: Diluting Capacitymentioning

confidence: 99%

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Renal Control of Sodium Homeostasis in Infancy

Thodenius

1974

Acta Paediatrica

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Section: Diuresissupporting

confidence: 54%

Section: Discussionmentioning

confidence: 99%

Section: Diluting Capacitymentioning

confidence: 99%

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Renal Control of Sodium Homeostasis in Infancy

Thodenius

1974

Acta Paediatrica

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“…1-217 ml on day 5. Jones et al [5], in a much smaller series, noted logarithmic variations (0.5-5.0ml/h/per kg). Equally, the practical difficulties of 24 h urine collections in infants are well known.…”

Section: Discussionmentioning

confidence: 89%

Urinary catecholamine levels in the newborn infant

1985

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The urinary concentrations of dopamine, noradrenaline and adrenaline were measured by a radioenzymatic method in 212 full-term and premature newborns. The ranges, means and standard deviations from birth to 4 days + are presented. The excretion of dopamine was ten times that of noradrenaline or adrenaline. The absolute concentrations of each catecholamine were reduced as birth weight decreased. The values were increased in babies with fetal distress. Any changes found in hypoglycaemic or jaundiced infants were attributable to prematurity. Very high levels were found in a few infants given tolazoline. We speculate that the role of dopamine production and excretion in the newborn has been underestimated. Dopamine may have an important role to play in the homeostatic mechanisms of the newborn.

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“…Previous data suggested that the rates of urea N excretion in the newborn infant may be much lower than those in the adults as a consequence of active growth (1). A later study by Jones et al (2) showed that the rates of urea N excretion in the urine of newborn infants were higher than previously suggested. Nevertheless, the urea excretion rate was much less than that estimated for the human fetus at term gestation by Gresham et al (3).…”

mentioning

confidence: 76%

Rates of Urea Synthesis in the Human Newborn: Effect of Maternal Diabetes and Small Size for Gestational Age

Kalhan

1993

Pediatr Res

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ABSTRACT. The rates of urea synthesis and glucose turnover were quantified during fasting using ["N2]urea and [6,62H2]glucose tracers with the prime constant rate infusion technique in 33 infants: 19 normal infants, 10 infants of diabetic mothers (IDM), and four small for gestational age (SGA) infants born at term gestation. All infants were studied during fasting 4 h after their last feed. Eleven normal infants and six IDM were studied soon after birth before any feeding. The rate of urea synthesis in normal infants was 5.84 + 2.0 mg of nitrogen (N)/kg* h-' or 3.5 rmol of urea/kg*min-'. The rate was slightly higher in IDM (7.09 + 3.0 mg N/kg-h-') and lower in SGA infants (4.59 f 1.22 mg N/kg-h-'); however, the differences were not statistically significant. No differences in urea synthesis were observed between infants studied soon after birth and those studied after initiation of feeding. The rate of appearance of glucose was lower in IDM infants studied during the first 6 h after birth (IDM 19.62 f 2.14 rmol/kg*min-', normal infants 24.03 f 4.05 rmol/ kgwmin-I, p = 0.01). However, rate of appearance of glucose in IDM infants studied between 17 and 20 h after birth was similar to that in normal infants. Rate of appearance of glucose was lower (not significantly) in SGA infants (17.7 f 3.3 pmol/kg*min-') as compared with normal infants. No correlation between rates of urea synthesis and glucose turnover was observed. These data show that newborn infants during fasting have an obligatory rate of protein oxidation of -0.87 g/kg*d-' and that maternal diabetes has no effect on it. The slightly lower rate of protein oxidation in SGA infants may be related to increased N assimilation. (Pediatr Res 34: 801-804, 1993) Abbreviations N, nitrogen IDM, infants of insulin-dependent diabetic mothers SGA, small for gestational age AGA, appropriate for gestational age Ra, rate of appearance Measurements of urea N excretion are performed to quantify nitrogen balance and rates of protein oxidation in infants and children. However, limited data are published in literature on the rates of urea synthesis or excretion in the human newborn. Previous data suggested that the rates of urea N excretion in the newborn infant may be much lower than those in the adults as (2) showed that the rates of urea N excretion in the urine of newborn infants were higher than previously suggested. Nevertheless, the urea excretion rate was much less than that estimated for the human fetus at term gestation by Gresham et al. (3). Inasmuch as urinary urea does not reflect the excretion of the total urea synthesized because of loss of urea by skin and possibly because of hydrolysis in the gut, the measurements of urea N excretion in urine will underestimate the actual rates of urea synthesis and therefore protein oxidation (4, 5). In fact, the rates of protein oxidation, as measured by oxidation rates of essential amino acids such as leucine (6, 7), suggest a much higher rate of protein oxidation in full-term newborn infants (-1.4 g/kg. d-I) as compar...

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Urinary Flow Rates and Urea Excretion Rates in Newborn Infants

Cited by 28 publications

References 8 publications

Renal Control of Sodium Homeostasis in Infancy

Renal Control of Sodium Homeostasis in Infancy

Urinary catecholamine levels in the newborn infant

Rates of Urea Synthesis in the Human Newborn: Effect of Maternal Diabetes and Small Size for Gestational Age

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