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Urinary sodium excretion in young infants: Role of gestational and postnatal ages
Author(s) -
KOO W. W. K.,
SUCCOP P.,
GUPTA J. M.
Publication year - 1988
Publication title -
journal of paediatrics and child health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.631
H-Index - 76
eISSN - 1440-1754
pISSN - 1034-4810
DOI - 10.1111/j.1440-1754.1988.tb00309.x
Subject(s) - medicine , gestational age , excretion , sodium , zoology , birth weight , urinary system , endocrinology , pregnancy , chemistry , biology , genetics , organic chemistry
Fractional urinary sodium excretion (FE Na ) and urinary sodium excretion (U Na E) were determined 88 times in 42 healthy, appropriate weight‐for‐gestational age infants. Gestational ages (GA) were 28–41 weeks; birthweights were 930–4135 g. Nineteen preterm infants were studied serially a total of 59 times between 1 and 55 days after birth. During the first 4 days after birth, multiple hierarchical regression analyses showed that FE Na and U Na E were inversely related to GA ( P < 0.001). Postnatal age (PN) was not significantly related to FE Na or U Na E. However the effect of GA on FE Na and U Na E was not significantly greater than the effect due to postnatal age (PA) ( P = 0.31 and P = 0.80, respectively). U Na E (1.6 ± 0.2 mmol/kg per day) was significantly greater than sodium intake (1.1 ± 0.2 mmol/kg per day) at 2.6 ± 0.2 days ( P < 0.05). Longitudinal studies extending beyond 4 days indicated that GA and PA had interactive effects on FE Na and U Na E; hence the contribution for a given GA was dependent on PA (and vice versa). Sodium intake remained stable (average 1.8 mmol/kg per day) beyond 7 days after birth and was consistently greater than U NA E ( P < 0.01). It is suggested that in healthy preterm infants beyond 2 weeks PA, a sodium intake of 2–3 mol/kg per day may be adequate to meet the renal sodium losses.