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Published on: February 9, 2021
Urinary mineral excretion in preterm neonates during the first month of life
Vasileios I Giapros1, Athanasios L Papaloukas, Styliani K Andronikou
1Neonatal Intensive Care Unit, Child Health Department, University of Ioannina, Ioannina, Greece. vgiapros@cc.uoi.gr
Insights
Urinary excretion of calcium, phosphate, and magnesium remains stable in preterm infants fed formula during their first month of life. However, urinary calcium, sodium, and magnesium levels show close correlations during this period.
Area of Science:
- Neonatal Medicine
- Pediatric Nephrology
- Biochemistry
Background:
- Urinary parameter estimation aids in identifying metabolic derangements in preterm infants.
- Monitoring renal excretion is crucial for understanding mineral balance in vulnerable neonates.
Purpose of the Study:
- To examine the variability and associations in renal excretion of calcium, magnesium, phosphate, and sodium.
- To assess these parameters in formula-fed preterm infants during the first month of life.
Main Methods:
- A prospective, longitudinal study of 34 preterm infants (<32 weeks gestational age).
- Serum and 8-hour urine mineral and creatinine concentrations were measured at three time points.
- Calculated urinary parameters included fractional excretion of sodium (FENa) and phosphate (FEP), and urinary calcium/creatinine (UCa/UCr) and magnesium/creatinine (UMg/UCr) ratios.
Main Results:
- Urinary excretion of calcium, phosphate, and magnesium remained stable throughout the first month.
- Sodium excretion showed a decline over the study period.
- Significant positive correlations were found between the excretion of calcium, magnesium, and sodium.
Conclusions:
- Urinary excretion of calcium, phosphate, and magnesium is stable in preterm formula-fed infants in the first month of life.
- Urinary calcium, sodium, and magnesium levels are closely correlated during this neonatal period.
Background:
Estimation of urinary parameters in preterm infants is a useful method for identifying metabolic derangements.
Objectives:
A prospective, longitudinal, hospital-based study was designed to examine the variability and the associations in renal excretion of calcium (Ca), magnesium (Mg), phosphate (P) and sodium (Na) in formula-fed preterm infants during the first month of life.
Patients:
Thirty-four infants <32 weeks gestational age, clinically stable, not receiving nephrotoxic drugs.
Methods:
Measurements of serum and 8-hour urinary mineral and creatinine (Cr) concentrations were made in all infants during three periods (at 7-10, 14-17 and 21-26 days postnatally). The urinary parameters, FENa, FEP, UCa/UCr, UMg/UCr were calculated. 24- hour urinary excretion was estimated by extrapolation of the 8-hour values.
Results:
The 24-hour excretion values (median and range) (mmol/kg) during the three study periods were, respectively, for Ca: 0.027 (0.015-0.15), 0.030 (0.007-0.12), 0.031 (0.008-0.12), for P: 0.26 (0.07-0.83), 0.29 (0.06-0.67), 0.41 (0.22-0.70), for Mg: 0.025 (0.007-0.14), 0.025 (0.008-0.16), 0.027 (0.010-0.10) and for Na: 2.85 (0.8-15), 1.45 (0.3-17), 1.56 (0.6-4.3). Na excretion declined while the excretion of the other minerals remained stable. A positive correlation was observed between excretion of Ca, Mg and Na (Ca vs. Na r = 0.63, p < 0.0001; Ca vs. Mg r = 0.65, p < 0.0001; Na vs. Mg r = 0.38, p = 0.012) as well as between the renal parameters FENa, FEP, UCa/UCr, UMg/UCr and the respective 24-hour excretion values (r = 0.80, 0.86, 0.84, 0.81) CONCLUSIONS: Urinary excretion of Ca, P, and Mg in preterm formula-fed infants is stable during the first month of life while urinary Ca, Na and Mg are closely correlated during the same period.
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